From 23deb06821442506615f34bd92ccd6a2422629d7 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 30 May 2008 17:19:03 -0700 Subject: x86: move x86-specific documentation into Documentation/x86 The current organization of the x86 documentation makes it appear as if the "i386" documentation doesn't apply to x86-64, which is does. Thus, move that documentation into Documentation/x86, and move the x86-64-specific stuff into Documentation/x86/x86_64 with the eventual goal to move stuff that isn't actually 64-bit specific back into Documentation/x86. Signed-off-by: H. Peter Anvin --- Documentation/i386/IO-APIC.txt | 119 ---- Documentation/i386/boot.txt | 900 ------------------------- Documentation/i386/usb-legacy-support.txt | 44 -- Documentation/i386/zero-page.txt | 31 - Documentation/x86/i386/IO-APIC.txt | 119 ++++ Documentation/x86/i386/boot.txt | 900 +++++++++++++++++++++++++ Documentation/x86/i386/usb-legacy-support.txt | 44 ++ Documentation/x86/i386/zero-page.txt | 31 + Documentation/x86/x86_64/00-INDEX | 16 + Documentation/x86/x86_64/boot-options.txt | 314 +++++++++ Documentation/x86/x86_64/cpu-hotplug-spec | 21 + Documentation/x86/x86_64/fake-numa-for-cpusets | 66 ++ Documentation/x86/x86_64/kernel-stacks | 99 +++ Documentation/x86/x86_64/machinecheck | 77 +++ Documentation/x86/x86_64/mm.txt | 29 + Documentation/x86/x86_64/uefi.txt | 38 ++ Documentation/x86_64/00-INDEX | 16 - Documentation/x86_64/boot-options.txt | 314 --------- Documentation/x86_64/cpu-hotplug-spec | 21 - Documentation/x86_64/fake-numa-for-cpusets | 66 -- Documentation/x86_64/kernel-stacks | 99 --- Documentation/x86_64/machinecheck | 77 --- Documentation/x86_64/mm.txt | 29 - Documentation/x86_64/uefi.txt | 38 -- 24 files changed, 1754 insertions(+), 1754 deletions(-) delete mode 100644 Documentation/i386/IO-APIC.txt delete mode 100644 Documentation/i386/boot.txt delete mode 100644 Documentation/i386/usb-legacy-support.txt delete mode 100644 Documentation/i386/zero-page.txt create mode 100644 Documentation/x86/i386/IO-APIC.txt create mode 100644 Documentation/x86/i386/boot.txt create mode 100644 Documentation/x86/i386/usb-legacy-support.txt create mode 100644 Documentation/x86/i386/zero-page.txt create mode 100644 Documentation/x86/x86_64/00-INDEX create mode 100644 Documentation/x86/x86_64/boot-options.txt create mode 100644 Documentation/x86/x86_64/cpu-hotplug-spec create mode 100644 Documentation/x86/x86_64/fake-numa-for-cpusets create mode 100644 Documentation/x86/x86_64/kernel-stacks create mode 100644 Documentation/x86/x86_64/machinecheck create mode 100644 Documentation/x86/x86_64/mm.txt create mode 100644 Documentation/x86/x86_64/uefi.txt delete mode 100644 Documentation/x86_64/00-INDEX delete mode 100644 Documentation/x86_64/boot-options.txt delete mode 100644 Documentation/x86_64/cpu-hotplug-spec delete mode 100644 Documentation/x86_64/fake-numa-for-cpusets delete mode 100644 Documentation/x86_64/kernel-stacks delete mode 100644 Documentation/x86_64/machinecheck delete mode 100644 Documentation/x86_64/mm.txt delete mode 100644 Documentation/x86_64/uefi.txt (limited to 'Documentation') diff --git a/Documentation/i386/IO-APIC.txt b/Documentation/i386/IO-APIC.txt deleted file mode 100644 index 30b4c714fbe..00000000000 --- a/Documentation/i386/IO-APIC.txt +++ /dev/null @@ -1,119 +0,0 @@ -Most (all) Intel-MP compliant SMP boards have the so-called 'IO-APIC', -which is an enhanced interrupt controller. It enables us to route -hardware interrupts to multiple CPUs, or to CPU groups. Without an -IO-APIC, interrupts from hardware will be delivered only to the -CPU which boots the operating system (usually CPU#0). - -Linux supports all variants of compliant SMP boards, including ones with -multiple IO-APICs. Multiple IO-APICs are used in high-end servers to -distribute IRQ load further. - -There are (a few) known breakages in certain older boards, such bugs are -usually worked around by the kernel. If your MP-compliant SMP board does -not boot Linux, then consult the linux-smp mailing list archives first. - -If your box boots fine with enabled IO-APIC IRQs, then your -/proc/interrupts will look like this one: - - ----------------------------> - hell:~> cat /proc/interrupts - CPU0 - 0: 1360293 IO-APIC-edge timer - 1: 4 IO-APIC-edge keyboard - 2: 0 XT-PIC cascade - 13: 1 XT-PIC fpu - 14: 1448 IO-APIC-edge ide0 - 16: 28232 IO-APIC-level Intel EtherExpress Pro 10/100 Ethernet - 17: 51304 IO-APIC-level eth0 - NMI: 0 - ERR: 0 - hell:~> - <---------------------------- - -Some interrupts are still listed as 'XT PIC', but this is not a problem; -none of those IRQ sources is performance-critical. - - -In the unlikely case that your board does not create a working mp-table, -you can use the pirq= boot parameter to 'hand-construct' IRQ entries. This -is non-trivial though and cannot be automated. One sample /etc/lilo.conf -entry: - - append="pirq=15,11,10" - -The actual numbers depend on your system, on your PCI cards and on their -PCI slot position. Usually PCI slots are 'daisy chained' before they are -connected to the PCI chipset IRQ routing facility (the incoming PIRQ1-4 -lines): - - ,-. ,-. ,-. ,-. ,-. - PIRQ4 ----| |-. ,-| |-. ,-| |-. ,-| |--------| | - |S| \ / |S| \ / |S| \ / |S| |S| - PIRQ3 ----|l|-. `/---|l|-. `/---|l|-. `/---|l|--------|l| - |o| \/ |o| \/ |o| \/ |o| |o| - PIRQ2 ----|t|-./`----|t|-./`----|t|-./`----|t|--------|t| - |1| /\ |2| /\ |3| /\ |4| |5| - PIRQ1 ----| |- `----| |- `----| |- `----| |--------| | - `-' `-' `-' `-' `-' - -Every PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD: - - ,-. - INTD--| | - |S| - INTC--|l| - |o| - INTB--|t| - |x| - INTA--| | - `-' - -These INTA-D PCI IRQs are always 'local to the card', their real meaning -depends on which slot they are in. If you look at the daisy chaining diagram, -a card in slot4, issuing INTA IRQ, it will end up as a signal on PIRQ4 of -the PCI chipset. Most cards issue INTA, this creates optimal distribution -between the PIRQ lines. (distributing IRQ sources properly is not a -necessity, PCI IRQs can be shared at will, but it's a good for performance -to have non shared interrupts). Slot5 should be used for videocards, they -do not use interrupts normally, thus they are not daisy chained either. - -so if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in -Slot2, then you'll have to specify this pirq= line: - - append="pirq=11,9" - -the following script tries to figure out such a default pirq= line from -your PCI configuration: - - echo -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g' - -note that this script wont work if you have skipped a few slots or if your -board does not do default daisy-chaining. (or the IO-APIC has the PIRQ pins -connected in some strange way). E.g. if in the above case you have your SCSI -card (IRQ11) in Slot3, and have Slot1 empty: - - append="pirq=0,9,11" - -[value '0' is a generic 'placeholder', reserved for empty (or non-IRQ emitting) -slots.] - -Generally, it's always possible to find out the correct pirq= settings, just -permute all IRQ numbers properly ... it will take some time though. An -'incorrect' pirq line will cause the booting process to hang, or a device -won't function properly (e.g. if it's inserted as a module). - -If you have 2 PCI buses, then you can use up to 8 pirq values, although such -boards tend to have a good configuration. - -Be prepared that it might happen that you need some strange pirq line: - - append="pirq=0,0,0,0,0,0,9,11" - -Use smart trial-and-error techniques to find out the correct pirq line ... - -Good luck and mail to linux-smp@vger.kernel.org or -linux-kernel@vger.kernel.org if you have any problems that are not covered -by this document. - --- mingo - diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt deleted file mode 100644 index 147bfe511cd..00000000000 --- a/Documentation/i386/boot.txt +++ /dev/null @@ -1,900 +0,0 @@ - THE LINUX/x86 BOOT PROTOCOL - --------------------------- - -On the x86 platform, the Linux kernel uses a rather complicated boot -convention. This has evolved partially due to historical aspects, as -well as the desire in the early days to have the kernel itself be a -bootable image, the complicated PC memory model and due to changed -expectations in the PC industry caused by the effective demise of -real-mode DOS as a mainstream operating system. - -Currently, the following versions of the Linux/x86 boot protocol exist. - -Old kernels: zImage/Image support only. Some very early kernels - may not even support a command line. - -Protocol 2.00: (Kernel 1.3.73) Added bzImage and initrd support, as - well as a formalized way to communicate between the - boot loader and the kernel. setup.S made relocatable, - although the traditional setup area still assumed - writable. - -Protocol 2.01: (Kernel 1.3.76) Added a heap overrun warning. - -Protocol 2.02: (Kernel 2.4.0-test3-pre3) New command line protocol. - Lower the conventional memory ceiling. No overwrite - of the traditional setup area, thus making booting - safe for systems which use the EBDA from SMM or 32-bit - BIOS entry points. zImage deprecated but still - supported. - -Protocol 2.03: (Kernel 2.4.18-pre1) Explicitly makes the highest possible - initrd address available to the bootloader. - -Protocol 2.04: (Kernel 2.6.14) Extend the syssize field to four bytes. - -Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable. - Introduce relocatable_kernel and kernel_alignment fields. - -Protocol 2.06: (Kernel 2.6.22) Added a field that contains the size of - the boot command line. - -Protocol 2.07: (Kernel 2.6.24) Added paravirtualised boot protocol. - Introduced hardware_subarch and hardware_subarch_data - and KEEP_SEGMENTS flag in load_flags. - -Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format - payload. Introduced payload_offset and payload length - fields to aid in locating the payload. - -Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical - pointer to single linked list of struct setup_data. - -**** MEMORY LAYOUT - -The traditional memory map for the kernel loader, used for Image or -zImage kernels, typically looks like: - - | | -0A0000 +------------------------+ - | Reserved for BIOS | Do not use. Reserved for BIOS EBDA. -09A000 +------------------------+ - | Command line | - | Stack/heap | For use by the kernel real-mode code. -098000 +------------------------+ - | Kernel setup | The kernel real-mode code. -090200 +------------------------+ - | Kernel boot sector | The kernel legacy boot sector. -090000 +------------------------+ - | Protected-mode kernel | The bulk of the kernel image. -010000 +------------------------+ - | Boot loader | <- Boot sector entry point 0000:7C00 -001000 +------------------------+ - | Reserved for MBR/BIOS | -000800 +------------------------+ - | Typically used by MBR | -000600 +------------------------+ - | BIOS use only | -000000 +------------------------+ - - -When using bzImage, the protected-mode kernel was relocated to -0x100000 ("high memory"), and the kernel real-mode block (boot sector, -setup, and stack/heap) was made relocatable to any address between -0x10000 and end of low memory. Unfortunately, in protocols 2.00 and -2.01 the 0x90000+ memory range is still used internally by the kernel; -the 2.02 protocol resolves that problem. - -It is desirable to keep the "memory ceiling" -- the highest point in -low memory touched by the boot loader -- as low as possible, since -some newer BIOSes have begun to allocate some rather large amounts of -memory, called the Extended BIOS Data Area, near the top of low -memory. The boot loader should use the "INT 12h" BIOS call to verify -how much low memory is available. - -Unfortunately, if INT 12h reports that the amount of memory is too -low, there is usually nothing the boot loader can do but to report an -error to the user. The boot loader should therefore be designed to -take up as little space in low memory as it reasonably can. For -zImage or old bzImage kernels, which need data written into the -0x90000 segment, the boot loader should make sure not to use memory -above the 0x9A000 point; too many BIOSes will break above that point. - -For a modern bzImage kernel with boot protocol version >= 2.02, a -memory layout like the following is suggested: - - ~ ~ - | Protected-mode kernel | -100000 +------------------------+ - | I/O memory hole | -0A0000 +------------------------+ - | Reserved for BIOS | Leave as much as possible unused - ~ ~ - | Command line | (Can also be below the X+10000 mark) -X+10000 +------------------------+ - | Stack/heap | For use by the kernel real-mode code. -X+08000 +------------------------+ - | Kernel setup | The kernel real-mode code. - | Kernel boot sector | The kernel legacy boot sector. -X +------------------------+ - | Boot loader | <- Boot sector entry point 0000:7C00 -001000 +------------------------+ - | Reserved for MBR/BIOS | -000800 +------------------------+ - | Typically used by MBR | -000600 +------------------------+ - | BIOS use only | -000000 +------------------------+ - -... where the address X is as low as the design of the boot loader -permits. - - -**** THE REAL-MODE KERNEL HEADER - -In the following text, and anywhere in the kernel boot sequence, "a -sector" refers to 512 bytes. It is independent of the actual sector -size of the underlying medium. - -The first step in loading a Linux kernel should be to load the -real-mode code (boot sector and setup code) and then examine the -following header at offset 0x01f1. The real-mode code can total up to -32K, although the boot loader may choose to load only the first two -sectors (1K) and then examine the bootup sector size. - -The header looks like: - -Offset Proto Name Meaning -/Size - -01F1/1 ALL(1 setup_sects The size of the setup in sectors -01F2/2 ALL root_flags If set, the root is mounted readonly -01F4/4 2.04+(2 syssize The size of the 32-bit code in 16-byte paras -01F8/2 ALL ram_size DO NOT USE - for bootsect.S use only -01FA/2 ALL vid_mode Video mode control -01FC/2 ALL root_dev Default root device number -01FE/2 ALL boot_flag 0xAA55 magic number -0200/2 2.00+ jump Jump instruction -0202/4 2.00+ header Magic signature "HdrS" -0206/2 2.00+ version Boot protocol version supported -0208/4 2.00+ realmode_swtch Boot loader hook (see below) -020C/2 2.00+ start_sys The load-low segment (0x1000) (obsolete) -020E/2 2.00+ kernel_version Pointer to kernel version string -0210/1 2.00+ type_of_loader Boot loader identifier -0211/1 2.00+ loadflags Boot protocol option flags -0212/2 2.00+ setup_move_size Move to high memory size (used with hooks) -0214/4 2.00+ code32_start Boot loader hook (see below) -0218/4 2.00+ ramdisk_image initrd load address (set by boot loader) -021C/4 2.00+ ramdisk_size initrd size (set by boot loader) -0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only -0224/2 2.01+ heap_end_ptr Free memory after setup end -0226/2 N/A pad1 Unused -0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line -022C/4 2.03+ initrd_addr_max Highest legal initrd address -0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel -0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not -0235/3 N/A pad2 Unused -0238/4 2.06+ cmdline_size Maximum size of the kernel command line -023C/4 2.07+ hardware_subarch Hardware subarchitecture -0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data -0248/4 2.08+ payload_offset Offset of kernel payload -024C/4 2.08+ payload_length Length of kernel payload -0250/8 2.09+ setup_data 64-bit physical pointer to linked list - of struct setup_data - -(1) For backwards compatibility, if the setup_sects field contains 0, the - real value is 4. - -(2) For boot protocol prior to 2.04, the upper two bytes of the syssize - field are unusable, which means the size of a bzImage kernel - cannot be determined. - -If the "HdrS" (0x53726448) magic number is not found at offset 0x202, -the boot protocol version is "old". Loading an old kernel, the -following parameters should be assumed: - - Image type = zImage - initrd not supported - Real-mode kernel must be located at 0x90000. - -Otherwise, the "version" field contains the protocol version, -e.g. protocol version 2.01 will contain 0x0201 in this field. When -setting fields in the header, you must make sure only to set fields -supported by the protocol version in use. - - -**** DETAILS OF HEADER FIELDS - -For each field, some are information from the kernel to the bootloader -("read"), some are expected to be filled out by the bootloader -("write"), and some are expected to be read and modified by the -bootloader ("modify"). - -All general purpose boot loaders should write the fields marked -(obligatory). Boot loaders who want to load the kernel at a -nonstandard address should fill in the fields marked (reloc); other -boot loaders can ignore those fields. - -The byte order of all fields is littleendian (this is x86, after all.) - -Field name: setup_sects -Type: read -Offset/size: 0x1f1/1 -Protocol: ALL - - The size of the setup code in 512-byte sectors. If this field is - 0, the real value is 4. The real-mode code consists of the boot - sector (always one 512-byte sector) plus the setup code. - -Field name: root_flags -Type: modify (optional) -Offset/size: 0x1f2/2 -Protocol: ALL - - If this field is nonzero, the root defaults to readonly. The use of - this field is deprecated; use the "ro" or "rw" options on the - command line instead. - -Field name: syssize -Type: read -Offset/size: 0x1f4/4 (protocol 2.04+) 0x1f4/2 (protocol ALL) -Protocol: 2.04+ - - The size of the protected-mode code in units of 16-byte paragraphs. - For protocol versions older than 2.04 this field is only two bytes - wide, and therefore cannot be trusted for the size of a kernel if - the LOAD_HIGH flag is set. - -Field name: ram_size -Type: kernel internal -Offset/size: 0x1f8/2 -Protocol: ALL - - This field is obsolete. - -Field name: vid_mode -Type: modify (obligatory) -Offset/size: 0x1fa/2 - - Please see the section on SPECIAL COMMAND LINE OPTIONS. - -Field name: root_dev -Type: modify (optional) -Offset/size: 0x1fc/2 -Protocol: ALL - - The default root device device number. The use of this field is - deprecated, use the "root=" option on the command line instead. - -Field name: boot_flag -Type: read -Offset/size: 0x1fe/2 -Protocol: ALL - - Contains 0xAA55. This is the closest thing old Linux kernels have - to a magic number. - -Field name: jump -Type: read -Offset/size: 0x200/2 -Protocol: 2.00+ - - Contains an x86 jump instruction, 0xEB followed by a signed offset - relative to byte 0x202. This can be used to determine the size of - the header. - -Field name: header -Type: read -Offset/size: 0x202/4 -Protocol: 2.00+ - - Contains the magic number "HdrS" (0x53726448). - -Field name: version -Type: read -Offset/size: 0x206/2 -Protocol: 2.00+ - - Contains the boot protocol version, in (major << 8)+minor format, - e.g. 0x0204 for version 2.04, and 0x0a11 for a hypothetical version - 10.17. - -Field name: readmode_swtch -Type: modify (optional) -Offset/size: 0x208/4 -Protocol: 2.00+ - - Boot loader hook (see ADVANCED BOOT LOADER HOOKS below.) - -Field name: start_sys -Type: read -Offset/size: 0x20c/4 -Protocol: 2.00+ - - The load low segment (0x1000). Obsolete. - -Field name: kernel_version -Type: read -Offset/size: 0x20e/2 -Protocol: 2.00+ - - If set to a nonzero value, contains a pointer to a NUL-terminated - human-readable kernel version number string, less 0x200. This can - be used to display the kernel version to the user. This value - should be less than (0x200*setup_sects). - - For example, if this value is set to 0x1c00, the kernel version - number string can be found at offset 0x1e00 in the kernel file. - This is a valid value if and only if the "setup_sects" field - contains the value 15 or higher, as: - - 0x1c00 < 15*0x200 (= 0x1e00) but - 0x1c00 >= 14*0x200 (= 0x1c00) - - 0x1c00 >> 9 = 14, so the minimum value for setup_secs is 15. - -Field name: type_of_loader -Type: write (obligatory) -Offset/size: 0x210/1 -Protocol: 2.00+ - - If your boot loader has an assigned id (see table below), enter - 0xTV here, where T is an identifier for the boot loader and V is - a version number. Otherwise, enter 0xFF here. - - Assigned boot loader ids: - 0 LILO (0x00 reserved for pre-2.00 bootloader) - 1 Loadlin - 2 bootsect-loader (0x20, all other values reserved) - 3 SYSLINUX - 4 EtherBoot - 5 ELILO - 7 GRuB - 8 U-BOOT - 9 Xen - A Gujin - B Qemu - - Please contact if you need a bootloader ID - value assigned. - -Field name: loadflags -Type: modify (obligatory) -Offset/size: 0x211/1 -Protocol: 2.00+ - - This field is a bitmask. - - Bit 0 (read): LOADED_HIGH - - If 0, the protected-mode code is loaded at 0x10000. - - If 1, the protected-mode code is loaded at 0x100000. - - Bit 5 (write): QUIET_FLAG - - If 0, print early messages. - - If 1, suppress early messages. - This requests to the kernel (decompressor and early - kernel) to not write early messages that require - accessing the display hardware directly. - - Bit 6 (write): KEEP_SEGMENTS - Protocol: 2.07+ - - If 0, reload the segment registers in the 32bit entry point. - - If 1, do not reload the segment registers in the 32bit entry point. - Assume that %cs %ds %ss %es are all set to flat segments with - a base of 0 (or the equivalent for their environment). - - Bit 7 (write): CAN_USE_HEAP - Set this bit to 1 to indicate that the value entered in the - heap_end_ptr is valid. If this field is clear, some setup code - functionality will be disabled. - -Field name: setup_move_size -Type: modify (obligatory) -Offset/size: 0x212/2 -Protocol: 2.00-2.01 - - When using protocol 2.00 or 2.01, if the real mode kernel is not - loaded at 0x90000, it gets moved there later in the loading - sequence. Fill in this field if you want additional data (such as - the kernel command line) moved in addition to the real-mode kernel - itself. - - The unit is bytes starting with the beginning of the boot sector. - - This field is can be ignored when the protocol is 2.02 or higher, or - if the real-mode code is loaded at 0x90000. - -Field name: code32_start -Type: modify (optional, reloc) -Offset/size: 0x214/4 -Protocol: 2.00+ - - The address to jump to in protected mode. This defaults to the load - address of the kernel, and can be used by the boot loader to - determine the proper load address. - - This field can be modified for two purposes: - - 1. as a boot loader hook (see ADVANCED BOOT LOADER HOOKS below.) - - 2. if a bootloader which does not install a hook loads a - relocatable kernel at a nonstandard address it will have to modify - this field to point to the load address. - -Field name: ramdisk_image -Type: write (obligatory) -Offset/size: 0x218/4 -Protocol: 2.00+ - - The 32-bit linear address of the initial ramdisk or ramfs. Leave at - zero if there is no initial ramdisk/ramfs. - -Field name: ramdisk_size -Type: write (obligatory) -Offset/size: 0x21c/4 -Protocol: 2.00+ - - Size of the initial ramdisk or ramfs. Leave at zero if there is no - initial ramdisk/ramfs. - -Field name: bootsect_kludge -Type: kernel internal -Offset/size: 0x220/4 -Protocol: 2.00+ - - This field is obsolete. - -Field name: heap_end_ptr -Type: write (obligatory) -Offset/size: 0x224/2 -Protocol: 2.01+ - - Set this field to the offset (from the beginning of the real-mode - code) of the end of the setup stack/heap, minus 0x0200. - -Field name: cmd_line_ptr -Type: write (obligatory) -Offset/size: 0x228/4 -Protocol: 2.02+ - - Set this field to the linear address of the kernel command line. - The kernel command line can be located anywhere between the end of - the setup heap and 0xA0000; it does not have to be located in the - same 64K segment as the real-mode code itself. - - Fill in this field even if your boot loader does not support a - command line, in which case you can point this to an empty string - (or better yet, to the string "auto".) If this field is left at - zero, the kernel will assume that your boot loader does not support - the 2.02+ protocol. - -Field name: initrd_addr_max -Type: read -Offset/size: 0x22c/4 -Protocol: 2.03+ - - The maximum address that may be occupied by the initial - ramdisk/ramfs contents. For boot protocols 2.02 or earlier, this - field is not present, and the maximum address is 0x37FFFFFF. (This - address is defined as the address of the highest safe byte, so if - your ramdisk is exactly 131072 bytes long and this field is - 0x37FFFFFF, you can start your ramdisk at 0x37FE0000.) - -Field name: kernel_alignment -Type: read (reloc) -Offset/size: 0x230/4 -Protocol: 2.05+ - - Alignment unit required by the kernel (if relocatable_kernel is true.) - -Field name: relocatable_kernel -Type: read (reloc) -Offset/size: 0x234/1 -Protocol: 2.05+ - - If this field is nonzero, the protected-mode part of the kernel can - be loaded at any address that satisfies the kernel_alignment field. - After loading, the boot loader must set the code32_start field to - point to the loaded code, or to a boot loader hook. - -Field name: cmdline_size -Type: read -Offset/size: 0x238/4 -Protocol: 2.06+ - - The maximum size of the command line without the terminating - zero. This means that the command line can contain at most - cmdline_size characters. With protocol version 2.05 and earlier, the - maximum size was 255. - -Field name: hardware_subarch -Type: write (optional, defaults to x86/PC) -Offset/size: 0x23c/4 -Protocol: 2.07+ - - In a paravirtualized environment the hardware low level architectural - pieces such as interrupt handling, page table handling, and - accessing process control registers needs to be done differently. - - This field allows the bootloader to inform the kernel we are in one - one of those environments. - - 0x00000000 The default x86/PC environment - 0x00000001 lguest - 0x00000002 Xen - -Field name: hardware_subarch_data -Type: write (subarch-dependent) -Offset/size: 0x240/8 -Protocol: 2.07+ - - A pointer to data that is specific to hardware subarch - This field is currently unused for the default x86/PC environment, - do not modify. - -Field name: payload_offset -Type: read -Offset/size: 0x248/4 -Protocol: 2.08+ - - If non-zero then this field contains the offset from the end of the - real-mode code to the payload. - - The payload may be compressed. The format of both the compressed and - uncompressed data should be determined using the standard magic - numbers. Currently only gzip compressed ELF is used. - -Field name: payload_length -Type: read -Offset/size: 0x24c/4 -Protocol: 2.08+ - - The length of the payload. - -Field name: setup_data -Type: write (special) -Offset/size: 0x250/8 -Protocol: 2.09+ - - The 64-bit physical pointer to NULL terminated single linked list of - struct setup_data. This is used to define a more extensible boot - parameters passing mechanism. The definition of struct setup_data is - as follow: - - struct setup_data { - u64 next; - u32 type; - u32 len; - u8 data[0]; - }; - - Where, the next is a 64-bit physical pointer to the next node of - linked list, the next field of the last node is 0; the type is used - to identify the contents of data; the len is the length of data - field; the data holds the real payload. - - This list may be modified at a number of points during the bootup - process. Therefore, when modifying this list one should always make - sure to consider the case where the linked list already contains - entries. - - -**** THE IMAGE CHECKSUM - -From boot protocol version 2.08 onwards the CRC-32 is calculated over -the entire file using the characteristic polynomial 0x04C11DB7 and an -initial remainder of 0xffffffff. The checksum is appended to the -file; therefore the CRC of the file up to the limit specified in the -syssize field of the header is always 0. - - -**** THE KERNEL COMMAND LINE - -The kernel command line has become an important way for the boot -loader to communicate with the kernel. Some of its options are also -relevant to the boot loader itself, see "special command line options" -below. - -The kernel command line is a null-terminated string. The maximum -length can be retrieved from the field cmdline_size. Before protocol -version 2.06, the maximum was 255 characters. A string that is too -long will be automatically truncated by the kernel. - -If the boot protocol version is 2.02 or later, the address of the -kernel command line is given by the header field cmd_line_ptr (see -above.) This address can be anywhere between the end of the setup -heap and 0xA0000. - -If the protocol version is *not* 2.02 or higher, the kernel -command line is entered using the following protocol: - - At offset 0x0020 (word), "cmd_line_magic", enter the magic - number 0xA33F. - - At offset 0x0022 (word), "cmd_line_offset", enter the offset - of the kernel command line (relative to the start of the - real-mode kernel). - - The kernel command line *must* be within the memory region - covered by setup_move_size, so you may need to adjust this - field. - - -**** MEMORY LAYOUT OF THE REAL-MODE CODE - -The real-mode code requires a stack/heap to be set up, as well as -memory allocated for the kernel command line. This needs to be done -in the real-mode accessible memory in bottom megabyte. - -It should be noted that modern machines often have a sizable Extended -BIOS Data Area (EBDA). As a result, it is advisable to use as little -of the low megabyte as possible. - -Unfortunately, under the following circumstances the 0x90000 memory -segment has to be used: - - - When loading a zImage kernel ((loadflags & 0x01) == 0). - - When loading a 2.01 or earlier boot protocol kernel. - - -> For the 2.00 and 2.01 boot protocols, the real-mode code - can be loaded at another address, but it is internally - relocated to 0x90000. For the "old" protocol, the - real-mode code must be loaded at 0x90000. - -When loading at 0x90000, avoid using memory above 0x9a000. - -For boot protocol 2.02 or higher, the command line does not have to be -located in the same 64K segment as the real-mode setup code; it is -thus permitted to give the stack/heap the full 64K segment and locate -the command line above it. - -The kernel command line should not be located below the real-mode -code, nor should it be located in high memory. - - -**** SAMPLE BOOT CONFIGURATION - -As a sample configuration, assume the following layout of the real -mode segment: - - When loading below 0x90000, use the entire segment: - - 0x0000-0x7fff Real mode kernel - 0x8000-0xdfff Stack and heap - 0xe000-0xffff Kernel command line - - When loading at 0x90000 OR the protocol version is 2.01 or earlier: - - 0x0000-0x7fff Real mode kernel - 0x8000-0x97ff Stack and heap - 0x9800-0x9fff Kernel command line - -Such a boot loader should enter the following fields in the header: - - unsigned long base_ptr; /* base address for real-mode segment */ - - if ( setup_sects == 0 ) { - setup_sects = 4; - } - - if ( protocol >= 0x0200 ) { - type_of_loader = ; - if ( loading_initrd ) { - ramdisk_image = ; - ramdisk_size = ; - } - - if ( protocol >= 0x0202 && loadflags & 0x01 ) - heap_end = 0xe000; - else - heap_end = 0x9800; - - if ( protocol >= 0x0201 ) { - heap_end_ptr = heap_end - 0x200; - loadflags |= 0x80; /* CAN_USE_HEAP */ - } - - if ( protocol >= 0x0202 ) { - cmd_line_ptr = base_ptr + heap_end; - strcpy(cmd_line_ptr, cmdline); - } else { - cmd_line_magic = 0xA33F; - cmd_line_offset = heap_end; - setup_move_size = heap_end + strlen(cmdline)+1; - strcpy(base_ptr+cmd_line_offset, cmdline); - } - } else { - /* Very old kernel */ - - heap_end = 0x9800; - - cmd_line_magic = 0xA33F; - cmd_line_offset = heap_end; - - /* A very old kernel MUST have its real-mode code - loaded at 0x90000 */ - - if ( base_ptr != 0x90000 ) { - /* Copy the real-mode kernel */ - memcpy(0x90000, base_ptr, (setup_sects+1)*512); - base_ptr = 0x90000; /* Relocated */ - } - - strcpy(0x90000+cmd_line_offset, cmdline); - - /* It is recommended to clear memory up to the 32K mark */ - memset(0x90000 + (setup_sects+1)*512, 0, - (64-(setup_sects+1))*512); - } - - -**** LOADING THE REST OF THE KERNEL - -The 32-bit (non-real-mode) kernel starts at offset (setup_sects+1)*512 -in the kernel file (again, if setup_sects == 0 the real value is 4.) -It should be loaded at address 0x10000 for Image/zImage kernels and -0x100000 for bzImage kernels. - -The kernel is a bzImage kernel if the protocol >= 2.00 and the 0x01 -bit (LOAD_HIGH) in the loadflags field is set: - - is_bzImage = (protocol >= 0x0200) && (loadflags & 0x01); - load_address = is_bzImage ? 0x100000 : 0x10000; - -Note that Image/zImage kernels can be up to 512K in size, and thus use -the entire 0x10000-0x90000 range of memory. This means it is pretty -much a requirement for these kernels to load the real-mode part at -0x90000. bzImage kernels allow much more flexibility. - - -**** SPECIAL COMMAND LINE OPTIONS - -If the command line provided by the boot loader is entered by the -user, the user may expect the following command line options to work. -They should normally not be deleted from the kernel command line even -though not all of them are actually meaningful to the kernel. Boot -loader authors who need additional command line options for the boot -loader itself should get them registered in -Documentation/kernel-parameters.txt to make sure they will not -conflict with actual kernel options now or in the future. - - vga= - here is either an integer (in C notation, either - decimal, octal, or hexadecimal) or one of the strings - "normal" (meaning 0xFFFF), "ext" (meaning 0xFFFE) or "ask" - (meaning 0xFFFD). This value should be entered into the - vid_mode field, as it is used by the kernel before the command - line is parsed. - - mem= - is an integer in C notation optionally followed by - (case insensitive) K, M, G, T, P or E (meaning << 10, << 20, - << 30, << 40, << 50 or << 60). This specifies the end of - memory to the kernel. This affects the possible placement of - an initrd, since an initrd should be placed near end of - memory. Note that this is an option to *both* the kernel and - the bootloader! - - initrd= - An initrd should be loaded. The meaning of is - obviously bootloader-dependent, and some boot loaders - (e.g. LILO) do not have such a command. - -In addition, some boot loaders add the following options to the -user-specified command line: - - BOOT_IMAGE= - The boot image which was loaded. Again, the meaning of - is obviously bootloader-dependent. - - auto - The kernel was booted without explicit user intervention. - -If these options are added by the boot loader, it is highly -recommended that they are located *first*, before the user-specified -or configuration-specified command line. Otherwise, "init=/bin/sh" -gets confused by the "auto" option. - - -**** RUNNING THE KERNEL - -The kernel is started by jumping to the kernel entry point, which is -located at *segment* offset 0x20 from the start of the real mode -kernel. This means that if you loaded your real-mode kernel code at -0x90000, the kernel entry point is 9020:0000. - -At entry, ds = es = ss should point to the start of the real-mode -kernel code (0x9000 if the code is loaded at 0x90000), sp should be -set up properly, normally pointing to the top of the heap, and -interrupts should be disabled. Furthermore, to guard against bugs in -the kernel, it is recommended that the boot loader sets fs = gs = ds = -es = ss. - -In our example from above, we would do: - - /* Note: in the case of the "old" kernel protocol, base_ptr must - be == 0x90000 at this point; see the previous sample code */ - - seg = base_ptr >> 4; - - cli(); /* Enter with interrupts disabled! */ - - /* Set up the real-mode kernel stack */ - _SS = seg; - _SP = heap_end; - - _DS = _ES = _FS = _GS = seg; - jmp_far(seg+0x20, 0); /* Run the kernel */ - -If your boot sector accesses a floppy drive, it is recommended to -switch off the floppy motor before running the kernel, since the -kernel boot leaves interrupts off and thus the motor will not be -switched off, especially if the loaded kernel has the floppy driver as -a demand-loaded module! - - -**** ADVANCED BOOT LOADER HOOKS - -If the boot loader runs in a particularly hostile environment (such as -LOADLIN, which runs under DOS) it may be impossible to follow the -standard memory location requirements. Such a boot loader may use the -following hooks that, if set, are invoked by the kernel at the -appropriate time. The use of these hooks should probably be -considered an absolutely last resort! - -IMPORTANT: All the hooks are required to preserve %esp, %ebp, %esi and -%edi across invocation. - - realmode_swtch: - A 16-bit real mode far subroutine invoked immediately before - entering protected mode. The default routine disables NMI, so - your routine should probably do so, too. - - code32_start: - A 32-bit flat-mode routine *jumped* to immediately after the - transition to protected mode, but before the kernel is - uncompressed. No segments, except CS, are guaranteed to be - set up (current kernels do, but older ones do not); you should - set them up to BOOT_DS (0x18) yourself. - - After completing your hook, you should jump to the address - that was in this field before your boot loader overwrote it - (relocated, if appropriate.) - - -**** 32-bit BOOT PROTOCOL - -For machine with some new BIOS other than legacy BIOS, such as EFI, -LinuxBIOS, etc, and kexec, the 16-bit real mode setup code in kernel -based on legacy BIOS can not be used, so a 32-bit boot protocol needs -to be defined. - -In 32-bit boot protocol, the first step in loading a Linux kernel -should be to setup the boot parameters (struct boot_params, -traditionally known as "zero page"). The memory for struct boot_params -should be allocated and initialized to all zero. Then the setup header -from offset 0x01f1 of kernel image on should be loaded into struct -boot_params and examined. The end of setup header can be calculated as -follow: - - 0x0202 + byte value at offset 0x0201 - -In addition to read/modify/write the setup header of the struct -boot_params as that of 16-bit boot protocol, the boot loader should -also fill the additional fields of the struct boot_params as that -described in zero-page.txt. - -After setupping the struct boot_params, the boot loader can load the -32/64-bit kernel in the same way as that of 16-bit boot protocol. - -In 32-bit boot protocol, the kernel is started by jumping to the -32-bit kernel entry point, which is the start address of loaded -32/64-bit kernel. - -At entry, the CPU must be in 32-bit protected mode with paging -disabled; a GDT must be loaded with the descriptors for selectors -__BOOT_CS(0x10) and __BOOT_DS(0x18); both descriptors must be 4G flat -segment; __BOOS_CS must have execute/read permission, and __BOOT_DS -must have read/write permission; CS must be __BOOT_CS and DS, ES, SS -must be __BOOT_DS; interrupt must be disabled; %esi must hold the base -address of the struct boot_params; %ebp, %edi and %ebx must be zero. diff --git a/Documentation/i386/usb-legacy-support.txt b/Documentation/i386/usb-legacy-support.txt deleted file mode 100644 index 1894cdfc69d..00000000000 --- a/Documentation/i386/usb-legacy-support.txt +++ /dev/null @@ -1,44 +0,0 @@ -USB Legacy support -~~~~~~~~~~~~~~~~~~ - -Vojtech Pavlik , January 2004 - - -Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a -feature that allows one to use the USB mouse and keyboard as if they were -their classic PS/2 counterparts. This means one can use an USB keyboard to -type in LILO for example. - -It has several drawbacks, though: - -1) On some machines, the emulated PS/2 mouse takes over even when no USB - mouse is present and a real PS/2 mouse is present. In that case the extra - features (wheel, extra buttons, touchpad mode) of the real PS/2 mouse may - not be available. - -2) If CONFIG_HIGHMEM64G is enabled, the PS/2 mouse emulation can cause - system crashes, because the SMM BIOS is not expecting to be in PAE mode. - The Intel E7505 is a typical machine where this happens. - -3) If AMD64 64-bit mode is enabled, again system crashes often happen, - because the SMM BIOS isn't expecting the CPU to be in 64-bit mode. The - BIOS manufacturers only test with Windows, and Windows doesn't do 64-bit - yet. - -Solutions: - -Problem 1) can be solved by loading the USB drivers prior to loading the -PS/2 mouse driver. Since the PS/2 mouse driver is in 2.6 compiled into -the kernel unconditionally, this means the USB drivers need to be -compiled-in, too. - -Problem 2) can currently only be solved by either disabling HIGHMEM64G -in the kernel config or USB Legacy support in the BIOS. A BIOS update -could help, but so far no such update exists. - -Problem 3) is usually fixed by a BIOS update. Check the board -manufacturers web site. If an update is not available, disable USB -Legacy support in the BIOS. If this alone doesn't help, try also adding -idle=poll on the kernel command line. The BIOS may be entering the SMM -on the HLT instruction as well. - diff --git a/Documentation/i386/zero-page.txt b/Documentation/i386/zero-page.txt deleted file mode 100644 index 169ad423a3d..00000000000 --- a/Documentation/i386/zero-page.txt +++ /dev/null @@ -1,31 +0,0 @@ -The additional fields in struct boot_params as a part of 32-bit boot -protocol of kernel. These should be filled by bootloader or 16-bit -real-mode setup code of the kernel. References/settings to it mainly -are in: - - include/asm-x86/bootparam.h - - -Offset Proto Name Meaning -/Size - -000/040 ALL screen_info Text mode or frame buffer information - (struct screen_info) -040/014 ALL apm_bios_info APM BIOS information (struct apm_bios_info) -060/010 ALL ist_info Intel SpeedStep (IST) BIOS support information - (struct ist_info) -080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!! -090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!! -0A0/010 ALL sys_desc_table System description table (struct sys_desc_table) -140/080 ALL edid_info Video mode setup (struct edid_info) -1C0/020 ALL efi_info EFI 32 information (struct efi_info) -1E0/004 ALL alk_mem_k Alternative mem check, in KB -1E4/004 ALL scratch Scratch field for the kernel setup code -1E8/001 ALL e820_entries Number of entries in e820_map (below) -1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below) -1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer - (below) -290/040 ALL edd_mbr_sig_buffer EDD MBR signatures -2D0/A00 ALL e820_map E820 memory map table - (array of struct e820entry) -D00/1EC ALL eddbuf EDD data (array of struct edd_info) diff --git a/Documentation/x86/i386/IO-APIC.txt b/Documentation/x86/i386/IO-APIC.txt new file mode 100644 index 00000000000..30b4c714fbe --- /dev/null +++ b/Documentation/x86/i386/IO-APIC.txt @@ -0,0 +1,119 @@ +Most (all) Intel-MP compliant SMP boards have the so-called 'IO-APIC', +which is an enhanced interrupt controller. It enables us to route +hardware interrupts to multiple CPUs, or to CPU groups. Without an +IO-APIC, interrupts from hardware will be delivered only to the +CPU which boots the operating system (usually CPU#0). + +Linux supports all variants of compliant SMP boards, including ones with +multiple IO-APICs. Multiple IO-APICs are used in high-end servers to +distribute IRQ load further. + +There are (a few) known breakages in certain older boards, such bugs are +usually worked around by the kernel. If your MP-compliant SMP board does +not boot Linux, then consult the linux-smp mailing list archives first. + +If your box boots fine with enabled IO-APIC IRQs, then your +/proc/interrupts will look like this one: + + ----------------------------> + hell:~> cat /proc/interrupts + CPU0 + 0: 1360293 IO-APIC-edge timer + 1: 4 IO-APIC-edge keyboard + 2: 0 XT-PIC cascade + 13: 1 XT-PIC fpu + 14: 1448 IO-APIC-edge ide0 + 16: 28232 IO-APIC-level Intel EtherExpress Pro 10/100 Ethernet + 17: 51304 IO-APIC-level eth0 + NMI: 0 + ERR: 0 + hell:~> + <---------------------------- + +Some interrupts are still listed as 'XT PIC', but this is not a problem; +none of those IRQ sources is performance-critical. + + +In the unlikely case that your board does not create a working mp-table, +you can use the pirq= boot parameter to 'hand-construct' IRQ entries. This +is non-trivial though and cannot be automated. One sample /etc/lilo.conf +entry: + + append="pirq=15,11,10" + +The actual numbers depend on your system, on your PCI cards and on their +PCI slot position. Usually PCI slots are 'daisy chained' before they are +connected to the PCI chipset IRQ routing facility (the incoming PIRQ1-4 +lines): + + ,-. ,-. ,-. ,-. ,-. + PIRQ4 ----| |-. ,-| |-. ,-| |-. ,-| |--------| | + |S| \ / |S| \ / |S| \ / |S| |S| + PIRQ3 ----|l|-. `/---|l|-. `/---|l|-. `/---|l|--------|l| + |o| \/ |o| \/ |o| \/ |o| |o| + PIRQ2 ----|t|-./`----|t|-./`----|t|-./`----|t|--------|t| + |1| /\ |2| /\ |3| /\ |4| |5| + PIRQ1 ----| |- `----| |- `----| |- `----| |--------| | + `-' `-' `-' `-' `-' + +Every PCI card emits a PCI IRQ, which can be INTA, INTB, INTC or INTD: + + ,-. + INTD--| | + |S| + INTC--|l| + |o| + INTB--|t| + |x| + INTA--| | + `-' + +These INTA-D PCI IRQs are always 'local to the card', their real meaning +depends on which slot they are in. If you look at the daisy chaining diagram, +a card in slot4, issuing INTA IRQ, it will end up as a signal on PIRQ4 of +the PCI chipset. Most cards issue INTA, this creates optimal distribution +between the PIRQ lines. (distributing IRQ sources properly is not a +necessity, PCI IRQs can be shared at will, but it's a good for performance +to have non shared interrupts). Slot5 should be used for videocards, they +do not use interrupts normally, thus they are not daisy chained either. + +so if you have your SCSI card (IRQ11) in Slot1, Tulip card (IRQ9) in +Slot2, then you'll have to specify this pirq= line: + + append="pirq=11,9" + +the following script tries to figure out such a default pirq= line from +your PCI configuration: + + echo -n pirq=; echo `scanpci | grep T_L | cut -c56-` | sed 's/ /,/g' + +note that this script wont work if you have skipped a few slots or if your +board does not do default daisy-chaining. (or the IO-APIC has the PIRQ pins +connected in some strange way). E.g. if in the above case you have your SCSI +card (IRQ11) in Slot3, and have Slot1 empty: + + append="pirq=0,9,11" + +[value '0' is a generic 'placeholder', reserved for empty (or non-IRQ emitting) +slots.] + +Generally, it's always possible to find out the correct pirq= settings, just +permute all IRQ numbers properly ... it will take some time though. An +'incorrect' pirq line will cause the booting process to hang, or a device +won't function properly (e.g. if it's inserted as a module). + +If you have 2 PCI buses, then you can use up to 8 pirq values, although such +boards tend to have a good configuration. + +Be prepared that it might happen that you need some strange pirq line: + + append="pirq=0,0,0,0,0,0,9,11" + +Use smart trial-and-error techniques to find out the correct pirq line ... + +Good luck and mail to linux-smp@vger.kernel.org or +linux-kernel@vger.kernel.org if you have any problems that are not covered +by this document. + +-- mingo + diff --git a/Documentation/x86/i386/boot.txt b/Documentation/x86/i386/boot.txt new file mode 100644 index 00000000000..147bfe511cd --- /dev/null +++ b/Documentation/x86/i386/boot.txt @@ -0,0 +1,900 @@ + THE LINUX/x86 BOOT PROTOCOL + --------------------------- + +On the x86 platform, the Linux kernel uses a rather complicated boot +convention. This has evolved partially due to historical aspects, as +well as the desire in the early days to have the kernel itself be a +bootable image, the complicated PC memory model and due to changed +expectations in the PC industry caused by the effective demise of +real-mode DOS as a mainstream operating system. + +Currently, the following versions of the Linux/x86 boot protocol exist. + +Old kernels: zImage/Image support only. Some very early kernels + may not even support a command line. + +Protocol 2.00: (Kernel 1.3.73) Added bzImage and initrd support, as + well as a formalized way to communicate between the + boot loader and the kernel. setup.S made relocatable, + although the traditional setup area still assumed + writable. + +Protocol 2.01: (Kernel 1.3.76) Added a heap overrun warning. + +Protocol 2.02: (Kernel 2.4.0-test3-pre3) New command line protocol. + Lower the conventional memory ceiling. No overwrite + of the traditional setup area, thus making booting + safe for systems which use the EBDA from SMM or 32-bit + BIOS entry points. zImage deprecated but still + supported. + +Protocol 2.03: (Kernel 2.4.18-pre1) Explicitly makes the highest possible + initrd address available to the bootloader. + +Protocol 2.04: (Kernel 2.6.14) Extend the syssize field to four bytes. + +Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable. + Introduce relocatable_kernel and kernel_alignment fields. + +Protocol 2.06: (Kernel 2.6.22) Added a field that contains the size of + the boot command line. + +Protocol 2.07: (Kernel 2.6.24) Added paravirtualised boot protocol. + Introduced hardware_subarch and hardware_subarch_data + and KEEP_SEGMENTS flag in load_flags. + +Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format + payload. Introduced payload_offset and payload length + fields to aid in locating the payload. + +Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical + pointer to single linked list of struct setup_data. + +**** MEMORY LAYOUT + +The traditional memory map for the kernel loader, used for Image or +zImage kernels, typically looks like: + + | | +0A0000 +------------------------+ + | Reserved for BIOS | Do not use. Reserved for BIOS EBDA. +09A000 +------------------------+ + | Command line | + | Stack/heap | For use by the kernel real-mode code. +098000 +------------------------+ + | Kernel setup | The kernel real-mode code. +090200 +------------------------+ + | Kernel boot sector | The kernel legacy boot sector. +090000 +------------------------+ + | Protected-mode kernel | The bulk of the kernel image. +010000 +------------------------+ + | Boot loader | <- Boot sector entry point 0000:7C00 +001000 +------------------------+ + | Reserved for MBR/BIOS | +000800 +------------------------+ + | Typically used by MBR | +000600 +------------------------+ + | BIOS use only | +000000 +------------------------+ + + +When using bzImage, the protected-mode kernel was relocated to +0x100000 ("high memory"), and the kernel real-mode block (boot sector, +setup, and stack/heap) was made relocatable to any address between +0x10000 and end of low memory. Unfortunately, in protocols 2.00 and +2.01 the 0x90000+ memory range is still used internally by the kernel; +the 2.02 protocol resolves that problem. + +It is desirable to keep the "memory ceiling" -- the highest point in +low memory touched by the boot loader -- as low as possible, since +some newer BIOSes have begun to allocate some rather large amounts of +memory, called the Extended BIOS Data Area, near the top of low +memory. The boot loader should use the "INT 12h" BIOS call to verify +how much low memory is available. + +Unfortunately, if INT 12h reports that the amount of memory is too +low, there is usually nothing the boot loader can do but to report an +error to the user. The boot loader should therefore be designed to +take up as little space in low memory as it reasonably can. For +zImage or old bzImage kernels, which need data written into the +0x90000 segment, the boot loader should make sure not to use memory +above the 0x9A000 point; too many BIOSes will break above that point. + +For a modern bzImage kernel with boot protocol version >= 2.02, a +memory layout like the following is suggested: + + ~ ~ + | Protected-mode kernel | +100000 +------------------------+ + | I/O memory hole | +0A0000 +------------------------+ + | Reserved for BIOS | Leave as much as possible unused + ~ ~ + | Command line | (Can also be below the X+10000 mark) +X+10000 +------------------------+ + | Stack/heap | For use by the kernel real-mode code. +X+08000 +------------------------+ + | Kernel setup | The kernel real-mode code. + | Kernel boot sector | The kernel legacy boot sector. +X +------------------------+ + | Boot loader | <- Boot sector entry point 0000:7C00 +001000 +------------------------+ + | Reserved for MBR/BIOS | +000800 +------------------------+ + | Typically used by MBR | +000600 +------------------------+ + | BIOS use only | +000000 +------------------------+ + +... where the address X is as low as the design of the boot loader +permits. + + +**** THE REAL-MODE KERNEL HEADER + +In the following text, and anywhere in the kernel boot sequence, "a +sector" refers to 512 bytes. It is independent of the actual sector +size of the underlying medium. + +The first step in loading a Linux kernel should be to load the +real-mode code (boot sector and setup code) and then examine the +following header at offset 0x01f1. The real-mode code can total up to +32K, although the boot loader may choose to load only the first two +sectors (1K) and then examine the bootup sector size. + +The header looks like: + +Offset Proto Name Meaning +/Size + +01F1/1 ALL(1 setup_sects The size of the setup in sectors +01F2/2 ALL root_flags If set, the root is mounted readonly +01F4/4 2.04+(2 syssize The size of the 32-bit code in 16-byte paras +01F8/2 ALL ram_size DO NOT USE - for bootsect.S use only +01FA/2 ALL vid_mode Video mode control +01FC/2 ALL root_dev Default root device number +01FE/2 ALL boot_flag 0xAA55 magic number +0200/2 2.00+ jump Jump instruction +0202/4 2.00+ header Magic signature "HdrS" +0206/2 2.00+ version Boot protocol version supported +0208/4 2.00+ realmode_swtch Boot loader hook (see below) +020C/2 2.00+ start_sys The load-low segment (0x1000) (obsolete) +020E/2 2.00+ kernel_version Pointer to kernel version string +0210/1 2.00+ type_of_loader Boot loader identifier +0211/1 2.00+ loadflags Boot protocol option flags +0212/2 2.00+ setup_move_size Move to high memory size (used with hooks) +0214/4 2.00+ code32_start Boot loader hook (see below) +0218/4 2.00+ ramdisk_image initrd load address (set by boot loader) +021C/4 2.00+ ramdisk_size initrd size (set by boot loader) +0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only +0224/2 2.01+ heap_end_ptr Free memory after setup end +0226/2 N/A pad1 Unused +0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line +022C/4 2.03+ initrd_addr_max Highest legal initrd address +0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel +0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not +0235/3 N/A pad2 Unused +0238/4 2.06+ cmdline_size Maximum size of the kernel command line +023C/4 2.07+ hardware_subarch Hardware subarchitecture +0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data +0248/4 2.08+ payload_offset Offset of kernel payload +024C/4 2.08+ payload_length Length of kernel payload +0250/8 2.09+ setup_data 64-bit physical pointer to linked list + of struct setup_data + +(1) For backwards compatibility, if the setup_sects field contains 0, the + real value is 4. + +(2) For boot protocol prior to 2.04, the upper two bytes of the syssize + field are unusable, which means the size of a bzImage kernel + cannot be determined. + +If the "HdrS" (0x53726448) magic number is not found at offset 0x202, +the boot protocol version is "old". Loading an old kernel, the +following parameters should be assumed: + + Image type = zImage + initrd not supported + Real-mode kernel must be located at 0x90000. + +Otherwise, the "version" field contains the protocol version, +e.g. protocol version 2.01 will contain 0x0201 in this field. When +setting fields in the header, you must make sure only to set fields +supported by the protocol version in use. + + +**** DETAILS OF HEADER FIELDS + +For each field, some are information from the kernel to the bootloader +("read"), some are expected to be filled out by the bootloader +("write"), and some are expected to be read and modified by the +bootloader ("modify"). + +All general purpose boot loaders should write the fields marked +(obligatory). Boot loaders who want to load the kernel at a +nonstandard address should fill in the fields marked (reloc); other +boot loaders can ignore those fields. + +The byte order of all fields is littleendian (this is x86, after all.) + +Field name: setup_sects +Type: read +Offset/size: 0x1f1/1 +Protocol: ALL + + The size of the setup code in 512-byte sectors. If this field is + 0, the real value is 4. The real-mode code consists of the boot + sector (always one 512-byte sector) plus the setup code. + +Field name: root_flags +Type: modify (optional) +Offset/size: 0x1f2/2 +Protocol: ALL + + If this field is nonzero, the root defaults to readonly. The use of + this field is deprecated; use the "ro" or "rw" options on the + command line instead. + +Field name: syssize +Type: read +Offset/size: 0x1f4/4 (protocol 2.04+) 0x1f4/2 (protocol ALL) +Protocol: 2.04+ + + The size of the protected-mode code in units of 16-byte paragraphs. + For protocol versions older than 2.04 this field is only two bytes + wide, and therefore cannot be trusted for the size of a kernel if + the LOAD_HIGH flag is set. + +Field name: ram_size +Type: kernel internal +Offset/size: 0x1f8/2 +Protocol: ALL + + This field is obsolete. + +Field name: vid_mode +Type: modify (obligatory) +Offset/size: 0x1fa/2 + + Please see the section on SPECIAL COMMAND LINE OPTIONS. + +Field name: root_dev +Type: modify (optional) +Offset/size: 0x1fc/2 +Protocol: ALL + + The default root device device number. The use of this field is + deprecated, use the "root=" option on the command line instead. + +Field name: boot_flag +Type: read +Offset/size: 0x1fe/2 +Protocol: ALL + + Contains 0xAA55. This is the closest thing old Linux kernels have + to a magic number. + +Field name: jump +Type: read +Offset/size: 0x200/2 +Protocol: 2.00+ + + Contains an x86 jump instruction, 0xEB followed by a signed offset + relative to byte 0x202. This can be used to determine the size of + the header. + +Field name: header +Type: read +Offset/size: 0x202/4 +Protocol: 2.00+ + + Contains the magic number "HdrS" (0x53726448). + +Field name: version +Type: read +Offset/size: 0x206/2 +Protocol: 2.00+ + + Contains the boot protocol version, in (major << 8)+minor format, + e.g. 0x0204 for version 2.04, and 0x0a11 for a hypothetical version + 10.17. + +Field name: readmode_swtch +Type: modify (optional) +Offset/size: 0x208/4 +Protocol: 2.00+ + + Boot loader hook (see ADVANCED BOOT LOADER HOOKS below.) + +Field name: start_sys +Type: read +Offset/size: 0x20c/4 +Protocol: 2.00+ + + The load low segment (0x1000). Obsolete. + +Field name: kernel_version +Type: read +Offset/size: 0x20e/2 +Protocol: 2.00+ + + If set to a nonzero value, contains a pointer to a NUL-terminated + human-readable kernel version number string, less 0x200. This can + be used to display the kernel version to the user. This value + should be less than (0x200*setup_sects). + + For example, if this value is set to 0x1c00, the kernel version + number string can be found at offset 0x1e00 in the kernel file. + This is a valid value if and only if the "setup_sects" field + contains the value 15 or higher, as: + + 0x1c00 < 15*0x200 (= 0x1e00) but + 0x1c00 >= 14*0x200 (= 0x1c00) + + 0x1c00 >> 9 = 14, so the minimum value for setup_secs is 15. + +Field name: type_of_loader +Type: write (obligatory) +Offset/size: 0x210/1 +Protocol: 2.00+ + + If your boot loader has an assigned id (see table below), enter + 0xTV here, where T is an identifier for the boot loader and V is + a version number. Otherwise, enter 0xFF here. + + Assigned boot loader ids: + 0 LILO (0x00 reserved for pre-2.00 bootloader) + 1 Loadlin + 2 bootsect-loader (0x20, all other values reserved) + 3 SYSLINUX + 4 EtherBoot + 5 ELILO + 7 GRuB + 8 U-BOOT + 9 Xen + A Gujin + B Qemu + + Please contact if you need a bootloader ID + value assigned. + +Field name: loadflags +Type: modify (obligatory) +Offset/size: 0x211/1 +Protocol: 2.00+ + + This field is a bitmask. + + Bit 0 (read): LOADED_HIGH + - If 0, the protected-mode code is loaded at 0x10000. + - If 1, the protected-mode code is loaded at 0x100000. + + Bit 5 (write): QUIET_FLAG + - If 0, print early messages. + - If 1, suppress early messages. + This requests to the kernel (decompressor and early + kernel) to not write early messages that require + accessing the display hardware directly. + + Bit 6 (write): KEEP_SEGMENTS + Protocol: 2.07+ + - If 0, reload the segment registers in the 32bit entry point. + - If 1, do not reload the segment registers in the 32bit entry point. + Assume that %cs %ds %ss %es are all set to flat segments with + a base of 0 (or the equivalent for their environment). + + Bit 7 (write): CAN_USE_HEAP + Set this bit to 1 to indicate that the value entered in the + heap_end_ptr is valid. If this field is clear, some setup code + functionality will be disabled. + +Field name: setup_move_size +Type: modify (obligatory) +Offset/size: 0x212/2 +Protocol: 2.00-2.01 + + When using protocol 2.00 or 2.01, if the real mode kernel is not + loaded at 0x90000, it gets moved there later in the loading + sequence. Fill in this field if you want additional data (such as + the kernel command line) moved in addition to the real-mode kernel + itself. + + The unit is bytes starting with the beginning of the boot sector. + + This field is can be ignored when the protocol is 2.02 or higher, or + if the real-mode code is loaded at 0x90000. + +Field name: code32_start +Type: modify (optional, reloc) +Offset/size: 0x214/4 +Protocol: 2.00+ + + The address to jump to in protected mode. This defaults to the load + address of the kernel, and can be used by the boot loader to + determine the proper load address. + + This field can be modified for two purposes: + + 1. as a boot loader hook (see ADVANCED BOOT LOADER HOOKS below.) + + 2. if a bootloader which does not install a hook loads a + relocatable kernel at a nonstandard address it will have to modify + this field to point to the load address. + +Field name: ramdisk_image +Type: write (obligatory) +Offset/size: 0x218/4 +Protocol: 2.00+ + + The 32-bit linear address of the initial ramdisk or ramfs. Leave at + zero if there is no initial ramdisk/ramfs. + +Field name: ramdisk_size +Type: write (obligatory) +Offset/size: 0x21c/4 +Protocol: 2.00+ + + Size of the initial ramdisk or ramfs. Leave at zero if there is no + initial ramdisk/ramfs. + +Field name: bootsect_kludge +Type: kernel internal +Offset/size: 0x220/4 +Protocol: 2.00+ + + This field is obsolete. + +Field name: heap_end_ptr +Type: write (obligatory) +Offset/size: 0x224/2 +Protocol: 2.01+ + + Set this field to the offset (from the beginning of the real-mode + code) of the end of the setup stack/heap, minus 0x0200. + +Field name: cmd_line_ptr +Type: write (obligatory) +Offset/size: 0x228/4 +Protocol: 2.02+ + + Set this field to the linear address of the kernel command line. + The kernel command line can be located anywhere between the end of + the setup heap and 0xA0000; it does not have to be located in the + same 64K segment as the real-mode code itself. + + Fill in this field even if your boot loader does not support a + command line, in which case you can point this to an empty string + (or better yet, to the string "auto".) If this field is left at + zero, the kernel will assume that your boot loader does not support + the 2.02+ protocol. + +Field name: initrd_addr_max +Type: read +Offset/size: 0x22c/4 +Protocol: 2.03+ + + The maximum address that may be occupied by the initial + ramdisk/ramfs contents. For boot protocols 2.02 or earlier, this + field is not present, and the maximum address is 0x37FFFFFF. (This + address is defined as the address of the highest safe byte, so if + your ramdisk is exactly 131072 bytes long and this field is + 0x37FFFFFF, you can start your ramdisk at 0x37FE0000.) + +Field name: kernel_alignment +Type: read (reloc) +Offset/size: 0x230/4 +Protocol: 2.05+ + + Alignment unit required by the kernel (if relocatable_kernel is true.) + +Field name: relocatable_kernel +Type: read (reloc) +Offset/size: 0x234/1 +Protocol: 2.05+ + + If this field is nonzero, the protected-mode part of the kernel can + be loaded at any address that satisfies the kernel_alignment field. + After loading, the boot loader must set the code32_start field to + point to the loaded code, or to a boot loader hook. + +Field name: cmdline_size +Type: read +Offset/size: 0x238/4 +Protocol: 2.06+ + + The maximum size of the command line without the terminating + zero. This means that the command line can contain at most + cmdline_size characters. With protocol version 2.05 and earlier, the + maximum size was 255. + +Field name: hardware_subarch +Type: write (optional, defaults to x86/PC) +Offset/size: 0x23c/4 +Protocol: 2.07+ + + In a paravirtualized environment the hardware low level architectural + pieces such as interrupt handling, page table handling, and + accessing process control registers needs to be done differently. + + This field allows the bootloader to inform the kernel we are in one + one of those environments. + + 0x00000000 The default x86/PC environment + 0x00000001 lguest + 0x00000002 Xen + +Field name: hardware_subarch_data +Type: write (subarch-dependent) +Offset/size: 0x240/8 +Protocol: 2.07+ + + A pointer to data that is specific to hardware subarch + This field is currently unused for the default x86/PC environment, + do not modify. + +Field name: payload_offset +Type: read +Offset/size: 0x248/4 +Protocol: 2.08+ + + If non-zero then this field contains the offset from the end of the + real-mode code to the payload. + + The payload may be compressed. The format of both the compressed and + uncompressed data should be determined using the standard magic + numbers. Currently only gzip compressed ELF is used. + +Field name: payload_length +Type: read +Offset/size: 0x24c/4 +Protocol: 2.08+ + + The length of the payload. + +Field name: setup_data +Type: write (special) +Offset/size: 0x250/8 +Protocol: 2.09+ + + The 64-bit physical pointer to NULL terminated single linked list of + struct setup_data. This is used to define a more extensible boot + parameters passing mechanism. The definition of struct setup_data is + as follow: + + struct setup_data { + u64 next; + u32 type; + u32 len; + u8 data[0]; + }; + + Where, the next is a 64-bit physical pointer to the next node of + linked list, the next field of the last node is 0; the type is used + to identify the contents of data; the len is the length of data + field; the data holds the real payload. + + This list may be modified at a number of points during the bootup + process. Therefore, when modifying this list one should always make + sure to consider the case where the linked list already contains + entries. + + +**** THE IMAGE CHECKSUM + +From boot protocol version 2.08 onwards the CRC-32 is calculated over +the entire file using the characteristic polynomial 0x04C11DB7 and an +initial remainder of 0xffffffff. The checksum is appended to the +file; therefore the CRC of the file up to the limit specified in the +syssize field of the header is always 0. + + +**** THE KERNEL COMMAND LINE + +The kernel command line has become an important way for the boot +loader to communicate with the kernel. Some of its options are also +relevant to the boot loader itself, see "special command line options" +below. + +The kernel command line is a null-terminated string. The maximum +length can be retrieved from the field cmdline_size. Before protocol +version 2.06, the maximum was 255 characters. A string that is too +long will be automatically truncated by the kernel. + +If the boot protocol version is 2.02 or later, the address of the +kernel command line is given by the header field cmd_line_ptr (see +above.) This address can be anywhere between the end of the setup +heap and 0xA0000. + +If the protocol version is *not* 2.02 or higher, the kernel +command line is entered using the following protocol: + + At offset 0x0020 (word), "cmd_line_magic", enter the magic + number 0xA33F. + + At offset 0x0022 (word), "cmd_line_offset", enter the offset + of the kernel command line (relative to the start of the + real-mode kernel). + + The kernel command line *must* be within the memory region + covered by setup_move_size, so you may need to adjust this + field. + + +**** MEMORY LAYOUT OF THE REAL-MODE CODE + +The real-mode code requires a stack/heap to be set up, as well as +memory allocated for the kernel command line. This needs to be done +in the real-mode accessible memory in bottom megabyte. + +It should be noted that modern machines often have a sizable Extended +BIOS Data Area (EBDA). As a result, it is advisable to use as little +of the low megabyte as possible. + +Unfortunately, under the following circumstances the 0x90000 memory +segment has to be used: + + - When loading a zImage kernel ((loadflags & 0x01) == 0). + - When loading a 2.01 or earlier boot protocol kernel. + + -> For the 2.00 and 2.01 boot protocols, the real-mode code + can be loaded at another address, but it is internally + relocated to 0x90000. For the "old" protocol, the + real-mode code must be loaded at 0x90000. + +When loading at 0x90000, avoid using memory above 0x9a000. + +For boot protocol 2.02 or higher, the command line does not have to be +located in the same 64K segment as the real-mode setup code; it is +thus permitted to give the stack/heap the full 64K segment and locate +the command line above it. + +The kernel command line should not be located below the real-mode +code, nor should it be located in high memory. + + +**** SAMPLE BOOT CONFIGURATION + +As a sample configuration, assume the following layout of the real +mode segment: + + When loading below 0x90000, use the entire segment: + + 0x0000-0x7fff Real mode kernel + 0x8000-0xdfff Stack and heap + 0xe000-0xffff Kernel command line + + When loading at 0x90000 OR the protocol version is 2.01 or earlier: + + 0x0000-0x7fff Real mode kernel + 0x8000-0x97ff Stack and heap + 0x9800-0x9fff Kernel command line + +Such a boot loader should enter the following fields in the header: + + unsigned long base_ptr; /* base address for real-mode segment */ + + if ( setup_sects == 0 ) { + setup_sects = 4; + } + + if ( protocol >= 0x0200 ) { + type_of_loader = ; + if ( loading_initrd ) { + ramdisk_image = ; + ramdisk_size = ; + } + + if ( protocol >= 0x0202 && loadflags & 0x01 ) + heap_end = 0xe000; + else + heap_end = 0x9800; + + if ( protocol >= 0x0201 ) { + heap_end_ptr = heap_end - 0x200; + loadflags |= 0x80; /* CAN_USE_HEAP */ + } + + if ( protocol >= 0x0202 ) { + cmd_line_ptr = base_ptr + heap_end; + strcpy(cmd_line_ptr, cmdline); + } else { + cmd_line_magic = 0xA33F; + cmd_line_offset = heap_end; + setup_move_size = heap_end + strlen(cmdline)+1; + strcpy(base_ptr+cmd_line_offset, cmdline); + } + } else { + /* Very old kernel */ + + heap_end = 0x9800; + + cmd_line_magic = 0xA33F; + cmd_line_offset = heap_end; + + /* A very old kernel MUST have its real-mode code + loaded at 0x90000 */ + + if ( base_ptr != 0x90000 ) { + /* Copy the real-mode kernel */ + memcpy(0x90000, base_ptr, (setup_sects+1)*512); + base_ptr = 0x90000; /* Relocated */ + } + + strcpy(0x90000+cmd_line_offset, cmdline); + + /* It is recommended to clear memory up to the 32K mark */ + memset(0x90000 + (setup_sects+1)*512, 0, + (64-(setup_sects+1))*512); + } + + +**** LOADING THE REST OF THE KERNEL + +The 32-bit (non-real-mode) kernel starts at offset (setup_sects+1)*512 +in the kernel file (again, if setup_sects == 0 the real value is 4.) +It should be loaded at address 0x10000 for Image/zImage kernels and +0x100000 for bzImage kernels. + +The kernel is a bzImage kernel if the protocol >= 2.00 and the 0x01 +bit (LOAD_HIGH) in the loadflags field is set: + + is_bzImage = (protocol >= 0x0200) && (loadflags & 0x01); + load_address = is_bzImage ? 0x100000 : 0x10000; + +Note that Image/zImage kernels can be up to 512K in size, and thus use +the entire 0x10000-0x90000 range of memory. This means it is pretty +much a requirement for these kernels to load the real-mode part at +0x90000. bzImage kernels allow much more flexibility. + + +**** SPECIAL COMMAND LINE OPTIONS + +If the command line provided by the boot loader is entered by the +user, the user may expect the following command line options to work. +They should normally not be deleted from the kernel command line even +though not all of them are actually meaningful to the kernel. Boot +loader authors who need additional command line options for the boot +loader itself should get them registered in +Documentation/kernel-parameters.txt to make sure they will not +conflict with actual kernel options now or in the future. + + vga= + here is either an integer (in C notation, either + decimal, octal, or hexadecimal) or one of the strings + "normal" (meaning 0xFFFF), "ext" (meaning 0xFFFE) or "ask" + (meaning 0xFFFD). This value should be entered into the + vid_mode field, as it is used by the kernel before the command + line is parsed. + + mem= + is an integer in C notation optionally followed by + (case insensitive) K, M, G, T, P or E (meaning << 10, << 20, + << 30, << 40, << 50 or << 60). This specifies the end of + memory to the kernel. This affects the possible placement of + an initrd, since an initrd should be placed near end of + memory. Note that this is an option to *both* the kernel and + the bootloader! + + initrd= + An initrd should be loaded. The meaning of is + obviously bootloader-dependent, and some boot loaders + (e.g. LILO) do not have such a command. + +In addition, some boot loaders add the following options to the +user-specified command line: + + BOOT_IMAGE= + The boot image which was loaded. Again, the meaning of + is obviously bootloader-dependent. + + auto + The kernel was booted without explicit user intervention. + +If these options are added by the boot loader, it is highly +recommended that they are located *first*, before the user-specified +or configuration-specified command line. Otherwise, "init=/bin/sh" +gets confused by the "auto" option. + + +**** RUNNING THE KERNEL + +The kernel is started by jumping to the kernel entry point, which is +located at *segment* offset 0x20 from the start of the real mode +kernel. This means that if you loaded your real-mode kernel code at +0x90000, the kernel entry point is 9020:0000. + +At entry, ds = es = ss should point to the start of the real-mode +kernel code (0x9000 if the code is loaded at 0x90000), sp should be +set up properly, normally pointing to the top of the heap, and +interrupts should be disabled. Furthermore, to guard against bugs in +the kernel, it is recommended that the boot loader sets fs = gs = ds = +es = ss. + +In our example from above, we would do: + + /* Note: in the case of the "old" kernel protocol, base_ptr must + be == 0x90000 at this point; see the previous sample code */ + + seg = base_ptr >> 4; + + cli(); /* Enter with interrupts disabled! */ + + /* Set up the real-mode kernel stack */ + _SS = seg; + _SP = heap_end; + + _DS = _ES = _FS = _GS = seg; + jmp_far(seg+0x20, 0); /* Run the kernel */ + +If your boot sector accesses a floppy drive, it is recommended to +switch off the floppy motor before running the kernel, since the +kernel boot leaves interrupts off and thus the motor will not be +switched off, especially if the loaded kernel has the floppy driver as +a demand-loaded module! + + +**** ADVANCED BOOT LOADER HOOKS + +If the boot loader runs in a particularly hostile environment (such as +LOADLIN, which runs under DOS) it may be impossible to follow the +standard memory location requirements. Such a boot loader may use the +following hooks that, if set, are invoked by the kernel at the +appropriate time. The use of these hooks should probably be +considered an absolutely last resort! + +IMPORTANT: All the hooks are required to preserve %esp, %ebp, %esi and +%edi across invocation. + + realmode_swtch: + A 16-bit real mode far subroutine invoked immediately before + entering protected mode. The default routine disables NMI, so + your routine should probably do so, too. + + code32_start: + A 32-bit flat-mode routine *jumped* to immediately after the + transition to protected mode, but before the kernel is + uncompressed. No segments, except CS, are guaranteed to be + set up (current kernels do, but older ones do not); you should + set them up to BOOT_DS (0x18) yourself. + + After completing your hook, you should jump to the address + that was in this field before your boot loader overwrote it + (relocated, if appropriate.) + + +**** 32-bit BOOT PROTOCOL + +For machine with some new BIOS other than legacy BIOS, such as EFI, +LinuxBIOS, etc, and kexec, the 16-bit real mode setup code in kernel +based on legacy BIOS can not be used, so a 32-bit boot protocol needs +to be defined. + +In 32-bit boot protocol, the first step in loading a Linux kernel +should be to setup the boot parameters (struct boot_params, +traditionally known as "zero page"). The memory for struct boot_params +should be allocated and initialized to all zero. Then the setup header +from offset 0x01f1 of kernel image on should be loaded into struct +boot_params and examined. The end of setup header can be calculated as +follow: + + 0x0202 + byte value at offset 0x0201 + +In addition to read/modify/write the setup header of the struct +boot_params as that of 16-bit boot protocol, the boot loader should +also fill the additional fields of the struct boot_params as that +described in zero-page.txt. + +After setupping the struct boot_params, the boot loader can load the +32/64-bit kernel in the same way as that of 16-bit boot protocol. + +In 32-bit boot protocol, the kernel is started by jumping to the +32-bit kernel entry point, which is the start address of loaded +32/64-bit kernel. + +At entry, the CPU must be in 32-bit protected mode with paging +disabled; a GDT must be loaded with the descriptors for selectors +__BOOT_CS(0x10) and __BOOT_DS(0x18); both descriptors must be 4G flat +segment; __BOOS_CS must have execute/read permission, and __BOOT_DS +must have read/write permission; CS must be __BOOT_CS and DS, ES, SS +must be __BOOT_DS; interrupt must be disabled; %esi must hold the base +address of the struct boot_params; %ebp, %edi and %ebx must be zero. diff --git a/Documentation/x86/i386/usb-legacy-support.txt b/Documentation/x86/i386/usb-legacy-support.txt new file mode 100644 index 00000000000..1894cdfc69d --- /dev/null +++ b/Documentation/x86/i386/usb-legacy-support.txt @@ -0,0 +1,44 @@ +USB Legacy support +~~~~~~~~~~~~~~~~~~ + +Vojtech Pavlik , January 2004 + + +Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a +feature that allows one to use the USB mouse and keyboard as if they were +their classic PS/2 counterparts. This means one can use an USB keyboard to +type in LILO for example. + +It has several drawbacks, though: + +1) On some machines, the emulated PS/2 mouse takes over even when no USB + mouse is present and a real PS/2 mouse is present. In that case the extra + features (wheel, extra buttons, touchpad mode) of the real PS/2 mouse may + not be available. + +2) If CONFIG_HIGHMEM64G is enabled, the PS/2 mouse emulation can cause + system crashes, because the SMM BIOS is not expecting to be in PAE mode. + The Intel E7505 is a typical machine where this happens. + +3) If AMD64 64-bit mode is enabled, again system crashes often happen, + because the SMM BIOS isn't expecting the CPU to be in 64-bit mode. The + BIOS manufacturers only test with Windows, and Windows doesn't do 64-bit + yet. + +Solutions: + +Problem 1) can be solved by loading the USB drivers prior to loading the +PS/2 mouse driver. Since the PS/2 mouse driver is in 2.6 compiled into +the kernel unconditionally, this means the USB drivers need to be +compiled-in, too. + +Problem 2) can currently only be solved by either disabling HIGHMEM64G +in the kernel config or USB Legacy support in the BIOS. A BIOS update +could help, but so far no such update exists. + +Problem 3) is usually fixed by a BIOS update. Check the board +manufacturers web site. If an update is not available, disable USB +Legacy support in the BIOS. If this alone doesn't help, try also adding +idle=poll on the kernel command line. The BIOS may be entering the SMM +on the HLT instruction as well. + diff --git a/Documentation/x86/i386/zero-page.txt b/Documentation/x86/i386/zero-page.txt new file mode 100644 index 00000000000..169ad423a3d --- /dev/null +++ b/Documentation/x86/i386/zero-page.txt @@ -0,0 +1,31 @@ +The additional fields in struct boot_params as a part of 32-bit boot +protocol of kernel. These should be filled by bootloader or 16-bit +real-mode setup code of the kernel. References/settings to it mainly +are in: + + include/asm-x86/bootparam.h + + +Offset Proto Name Meaning +/Size + +000/040 ALL screen_info Text mode or frame buffer information + (struct screen_info) +040/014 ALL apm_bios_info APM BIOS information (struct apm_bios_info) +060/010 ALL ist_info Intel SpeedStep (IST) BIOS support information + (struct ist_info) +080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!! +090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!! +0A0/010 ALL sys_desc_table System description table (struct sys_desc_table) +140/080 ALL edid_info Video mode setup (struct edid_info) +1C0/020 ALL efi_info EFI 32 information (struct efi_info) +1E0/004 ALL alk_mem_k Alternative mem check, in KB +1E4/004 ALL scratch Scratch field for the kernel setup code +1E8/001 ALL e820_entries Number of entries in e820_map (below) +1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below) +1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer + (below) +290/040 ALL edd_mbr_sig_buffer EDD MBR signatures +2D0/A00 ALL e820_map E820 memory map table + (array of struct e820entry) +D00/1EC ALL eddbuf EDD data (array of struct edd_info) diff --git a/Documentation/x86/x86_64/00-INDEX b/Documentation/x86/x86_64/00-INDEX new file mode 100644 index 00000000000..92fc20ab5f0 --- /dev/null +++ b/Documentation/x86/x86_64/00-INDEX @@ -0,0 +1,16 @@ +00-INDEX + - This file +boot-options.txt + - AMD64-specific boot options. +cpu-hotplug-spec + - Firmware support for CPU hotplug under Linux/x86-64 +fake-numa-for-cpusets + - Using numa=fake and CPUSets for Resource Management +kernel-stacks + - Context-specific per-processor interrupt stacks. +machinecheck + - Configurable sysfs parameters for the x86-64 machine check code. +mm.txt + - Memory layout of x86-64 (4 level page tables, 46 bits physical). +uefi.txt + - Booting Linux via Unified Extensible Firmware Interface. diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt new file mode 100644 index 00000000000..b0c7b6c4abd --- /dev/null +++ b/Documentation/x86/x86_64/boot-options.txt @@ -0,0 +1,314 @@ +AMD64 specific boot options + +There are many others (usually documented in driver documentation), but +only the AMD64 specific ones are listed here. + +Machine check + + mce=off disable machine check + mce=bootlog Enable logging of machine checks left over from booting. + Disabled by default on AMD because some BIOS leave bogus ones. + If your BIOS doesn't do that it's a good idea to enable though + to make sure you log even machine check events that result + in a reboot. On Intel systems it is enabled by default. + mce=nobootlog + Disable boot machine check logging. + mce=tolerancelevel (number) + 0: always panic on uncorrected errors, log corrected errors + 1: panic or SIGBUS on uncorrected errors, log corrected errors + 2: SIGBUS or log uncorrected errors, log corrected errors + 3: never panic or SIGBUS, log all errors (for testing only) + Default is 1 + Can be also set using sysfs which is preferable. + + nomce (for compatibility with i386): same as mce=off + + Everything else is in sysfs now. + +APICs + + apic Use IO-APIC. Default + + noapic Don't use the IO-APIC. + + disableapic Don't use the local APIC + + nolapic Don't use the local APIC (alias for i386 compatibility) + + pirq=... See Documentation/i386/IO-APIC.txt + + noapictimer Don't set up the APIC timer + + no_timer_check Don't check the IO-APIC timer. This can work around + problems with incorrect timer initialization on some boards. + + apicmaintimer Run time keeping from the local APIC timer instead + of using the PIT/HPET interrupt for this. This is useful + when the PIT/HPET interrupts are unreliable. + + noapicmaintimer Don't do time keeping using the APIC timer. + Useful when this option was auto selected, but doesn't work. + + apicpmtimer + Do APIC timer calibration using the pmtimer. Implies + apicmaintimer. Useful when your PIT timer is totally + broken. + + disable_8254_timer / enable_8254_timer + Enable interrupt 0 timer routing over the 8254 in addition to over + the IO-APIC. The kernel tries to set a sensible default. + +Early Console + + syntax: earlyprintk=vga + earlyprintk=serial[,ttySn[,baudrate]] + + The early console is useful when the kernel crashes before the + normal console is initialized. It is not enabled by + default because it has some cosmetic problems. + Append ,keep to not disable it when the real console takes over. + Only vga or serial at a time, not both. + Currently only ttyS0 and ttyS1 are supported. + Interaction with the standard serial driver is not very good. + The VGA output is eventually overwritten by the real console. + +Timing + + notsc + Don't use the CPU time stamp counter to read the wall time. + This can be used to work around timing problems on multiprocessor systems + with not properly synchronized CPUs. + + report_lost_ticks + Report when timer interrupts are lost because some code turned off + interrupts for too long. + + nmi_watchdog=NUMBER[,panic] + NUMBER can be: + 0 don't use an NMI watchdog + 1 use the IO-APIC timer for the NMI watchdog + 2 use the local APIC for the NMI watchdog using a performance counter. Note + This will use one performance counter and the local APIC's performance + vector. + When panic is specified panic when an NMI watchdog timeout occurs. + This is useful when you use a panic=... timeout and need the box + quickly up again. + + nohpet + Don't use the HPET timer. + +Idle loop + + idle=poll + Don't do power saving in the idle loop using HLT, but poll for rescheduling + event. This will make the CPUs eat a lot more power, but may be useful + to get slightly better performance in multiprocessor benchmarks. It also + makes some profiling using performance counters more accurate. + Please note that on systems with MONITOR/MWAIT support (like Intel EM64T + CPUs) this option has no performance advantage over the normal idle loop. + It may also interact badly with hyperthreading. + +Rebooting + + reboot=b[ios] | t[riple] | k[bd] | a[cpi] | e[fi] [, [w]arm | [c]old] + bios Use the CPU reboot vector for warm reset + warm Don't set the cold reboot flag + cold Set the cold reboot flag + triple Force a triple fault (init) + kbd Use the keyboard controller. cold reset (default) + acpi Use the ACPI RESET_REG in the FADT. If ACPI is not configured or the + ACPI reset does not work, the reboot path attempts the reset using + the keyboard controller. + efi Use efi reset_system runtime service. If EFI is not configured or the + EFI reset does not work, the reboot path attempts the reset using + the keyboard controller. + + Using warm reset will be much faster especially on big memory + systems because the BIOS will not go through the memory check. + Disadvantage is that not all hardware will be completely reinitialized + on reboot so there may be boot problems on some systems. + + reboot=force + + Don't stop other CPUs on reboot. This can make reboot more reliable + in some cases. + +Non Executable Mappings + + noexec=on|off + + on Enable(default) + off Disable + +SMP + + additional_cpus=NUM Allow NUM more CPUs for hotplug + (defaults are specified by the BIOS, see Documentation/x86_64/cpu-hotplug-spec) + +NUMA + + numa=off Only set up a single NUMA node spanning all memory. + + numa=noacpi Don't parse the SRAT table for NUMA setup + + numa=fake=CMDLINE + If a number, fakes CMDLINE nodes and ignores NUMA setup of the + actual machine. Otherwise, system memory is configured + depending on the sizes and coefficients listed. For example: + numa=fake=2*512,1024,4*256,*128 + gives two 512M nodes, a 1024M node, four 256M nodes, and the + rest split into 128M chunks. If the last character of CMDLINE + is a *, the remaining memory is divided up equally among its + coefficient: + numa=fake=2*512,2* + gives two 512M nodes and the rest split into two nodes. + Otherwise, the remaining system RAM is allocated to an + additional node. + + numa=hotadd=percent + Only allow hotadd memory to preallocate page structures upto + percent of already available memory. + numa=hotadd=0 will disable hotadd memory. + +ACPI + + acpi=off Don't enable ACPI + acpi=ht Use ACPI boot table parsing, but don't enable ACPI + interpreter + acpi=force Force ACPI on (currently not needed) + + acpi=strict Disable out of spec ACPI workarounds. + + acpi_sci={edge,level,high,low} Set up ACPI SCI interrupt. + + acpi=noirq Don't route interrupts + +PCI + + pci=off Don't use PCI + pci=conf1 Use conf1 access. + pci=conf2 Use conf2 access. + pci=rom Assign ROMs. + pci=assign-busses Assign busses + pci=irqmask=MASK Set PCI interrupt mask to MASK + pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says. + pci=noacpi Don't use ACPI to set up PCI interrupt routing. + +IOMMU (input/output memory management unit) + + Currently four x86-64 PCI-DMA mapping implementations exist: + + 1. : use no hardware/software IOMMU at all + (e.g. because you have < 3 GB memory). + Kernel boot message: "PCI-DMA: Disabling IOMMU" + + 2. : AMD GART based hardware IOMMU. + Kernel boot message: "PCI-DMA: using GART IOMMU" + + 3. : Software IOMMU implementation. Used + e.g. if there is no hardware IOMMU in the system and it is need because + you have >3GB memory or told the kernel to us it (iommu=soft)) + Kernel boot message: "PCI-DMA: Using software bounce buffering + for IO (SWIOTLB)" + + 4. : IBM Calgary hardware IOMMU. Used in IBM + pSeries and xSeries servers. This hardware IOMMU supports DMA address + mapping with memory protection, etc. + Kernel boot message: "PCI-DMA: Using Calgary IOMMU" + + iommu=[][,noagp][,off][,force][,noforce][,leak[=] + [,memaper[=]][,merge][,forcesac][,fullflush][,nomerge] + [,noaperture][,calgary] + + General iommu options: + off Don't initialize and use any kind of IOMMU. + noforce Don't force hardware IOMMU usage when it is not needed. + (default). + force Force the use of the hardware IOMMU even when it is + not actually needed (e.g. because < 3 GB memory). + soft Use software bounce buffering (SWIOTLB) (default for + Intel machines). This can be used to prevent the usage + of an available hardware IOMMU. + + iommu options only relevant to the AMD GART hardware IOMMU: + Set the size of the remapping area in bytes. + allowed Overwrite iommu off workarounds for specific chipsets. + fullflush Flush IOMMU on each allocation (default). + nofullflush Don't use IOMMU fullflush. + leak Turn on simple iommu leak tracing (only when + CONFIG_IOMMU_LEAK is on). Default number of leak pages + is 20. + memaper[=] Allocate an own aperture over RAM with size 32MB<4GB. + DAC is used with 32-bit PCI to push a 64-bit address in + two cycles. When off all DMA over >4GB is forced through + an IOMMU or software bounce buffering. + nodac Forbid DAC mode, i.e. DMA >4GB. + panic Always panic when IOMMU overflows. + calgary Use the Calgary IOMMU if it is available + + iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU + implementation: + swiotlb=[,force] + Prereserve that many 128K pages for the software IO + bounce buffering. + force Force all IO through the software TLB. + + Settings for the IBM Calgary hardware IOMMU currently found in IBM + pSeries and xSeries machines: + + calgary=[64k,128k,256k,512k,1M,2M,4M,8M] + calgary=[translate_empty_slots] + calgary=[disable=] + panic Always panic when IOMMU overflows + + 64k,...,8M - Set the size of each PCI slot's translation table + when using the Calgary IOMMU. This is the size of the translation + table itself in main memory. The smallest table, 64k, covers an IO + space of 32MB; the largest, 8MB table, can cover an IO space of + 4GB. Normally the kernel will make the right choice by itself. + + translate_empty_slots - Enable translation even on slots that have + no devices attached to them, in case a device will be hotplugged + in the future. + + disable= - Disable translation on a given PHB. For + example, the built-in graphics adapter resides on the first bridge + (PCI bus number 0); if translation (isolation) is enabled on this + bridge, X servers that access the hardware directly from user + space might stop working. Use this option if you have devices that + are accessed from userspace directly on some PCI host bridge. + +Debugging + + oops=panic Always panic on oopses. Default is to just kill the process, + but there is a small probability of deadlocking the machine. + This will also cause panics on machine check exceptions. + Useful together with panic=30 to trigger a reboot. + + kstack=N Print N words from the kernel stack in oops dumps. + + pagefaulttrace Dump all page faults. Only useful for extreme debugging + and will create a lot of output. + + call_trace=[old|both|newfallback|new] + old: use old inexact backtracer + new: use new exact dwarf2 unwinder + both: print entries from both + newfallback: use new unwinder but fall back to old if it gets + stuck (default) + +Miscellaneous + + nogbpages + Do not use GB pages for kernel direct mappings. + gbpages + Use GB pages for kernel direct mappings. diff --git a/Documentation/x86/x86_64/cpu-hotplug-spec b/Documentation/x86/x86_64/cpu-hotplug-spec new file mode 100644 index 00000000000..3c23e0587db --- /dev/null +++ b/Documentation/x86/x86_64/cpu-hotplug-spec @@ -0,0 +1,21 @@ +Firmware support for CPU hotplug under Linux/x86-64 +--------------------------------------------------- + +Linux/x86-64 supports CPU hotplug now. For various reasons Linux wants to +know in advance of boot time the maximum number of CPUs that could be plugged +into the system. ACPI 3.0 currently has no official way to supply +this information from the firmware to the operating system. + +In ACPI each CPU needs an LAPIC object in the MADT table (5.2.11.5 in the +ACPI 3.0 specification). ACPI already has the concept of disabled LAPIC +objects by setting the Enabled bit in the LAPIC object to zero. + +For CPU hotplug Linux/x86-64 expects now that any possible future hotpluggable +CPU is already available in the MADT. If the CPU is not available yet +it should have its LAPIC Enabled bit set to 0. Linux will use the number +of disabled LAPICs to compute the maximum number of future CPUs. + +In the worst case the user can overwrite this choice using a command line +option (additional_cpus=...), but it is recommended to supply the correct +number (or a reasonable approximation of it, with erring towards more not less) +in the MADT to avoid manual configuration. diff --git a/Documentation/x86/x86_64/fake-numa-for-cpusets b/Documentation/x86/x86_64/fake-numa-for-cpusets new file mode 100644 index 00000000000..d1a985c5b00 --- /dev/null +++ b/Documentation/x86/x86_64/fake-numa-for-cpusets @@ -0,0 +1,66 @@ +Using numa=fake and CPUSets for Resource Management +Written by David Rientjes + +This document describes how the numa=fake x86_64 command-line option can be used +in conjunction with cpusets for coarse memory management. Using this feature, +you can create fake NUMA nodes that represent contiguous chunks of memory and +assign them to cpusets and their attached tasks. This is a way of limiting the +amount of system memory that are available to a certain class of tasks. + +For more information on the features of cpusets, see Documentation/cpusets.txt. +There are a number of different configurations you can use for your needs. For +more information on the numa=fake command line option and its various ways of +configuring fake nodes, see Documentation/x86_64/boot-options.txt. + +For the purposes of this introduction, we'll assume a very primitive NUMA +emulation setup of "numa=fake=4*512,". This will split our system memory into +four equal chunks of 512M each that we can now use to assign to cpusets. As +you become more familiar with using this combination for resource control, +you'll determine a better setup to minimize the number of nodes you have to deal +with. + +A machine may be split as follows with "numa=fake=4*512," as reported by dmesg: + + Faking node 0 at 0000000000000000-0000000020000000 (512MB) + Faking node 1 at 0000000020000000-0000000040000000 (512MB) + Faking node 2 at 0000000040000000-0000000060000000 (512MB) + Faking node 3 at 0000000060000000-0000000080000000 (512MB) + ... + On node 0 totalpages: 130975 + On node 1 totalpages: 131072 + On node 2 totalpages: 131072 + On node 3 totalpages: 131072 + +Now following the instructions for mounting the cpusets filesystem from +Documentation/cpusets.txt, you can assign fake nodes (i.e. contiguous memory +address spaces) to individual cpusets: + + [root@xroads /]# mkdir exampleset + [root@xroads /]# mount -t cpuset none exampleset + [root@xroads /]# mkdir exampleset/ddset + [root@xroads /]# cd exampleset/ddset + [root@xroads /exampleset/ddset]# echo 0-1 > cpus + [root@xroads /exampleset/ddset]# echo 0-1 > mems + +Now this cpuset, 'ddset', will only allowed access to fake nodes 0 and 1 for +memory allocations (1G). + +You can now assign tasks to these cpusets to limit the memory resources +available to them according to the fake nodes assigned as mems: + + [root@xroads /exampleset/ddset]# echo $$ > tasks + [root@xroads /exampleset/ddset]# dd if=/dev/zero of=tmp bs=1024 count=1G + [1] 13425 + +Notice the difference between the system memory usage as reported by +/proc/meminfo between the restricted cpuset case above and the unrestricted +case (i.e. running the same 'dd' command without assigning it to a fake NUMA +cpuset): + Unrestricted Restricted + MemTotal: 3091900 kB 3091900 kB + MemFree: 42113 kB 1513236 kB + +This allows for coarse memory management for the tasks you assign to particular +cpusets. Since cpusets can form a hierarchy, you can create some pretty +interesting combinations of use-cases for various classes of tasks for your +memory management needs. diff --git a/Documentation/x86/x86_64/kernel-stacks b/Documentation/x86/x86_64/kernel-stacks new file mode 100644 index 00000000000..5ad65d51fb9 --- /dev/null +++ b/Documentation/x86/x86_64/kernel-stacks @@ -0,0 +1,99 @@ +Most of the text from Keith Owens, hacked by AK + +x86_64 page size (PAGE_SIZE) is 4K. + +Like all other architectures, x86_64 has a kernel stack for every +active thread. These thread stacks are THREAD_SIZE (2*PAGE_SIZE) big. +These stacks contain useful data as long as a thread is alive or a +zombie. While the thread is in user space the kernel stack is empty +except for the thread_info structure at the bottom. + +In addition to the per thread stacks, there are specialized stacks +associated with each CPU. These stacks are only used while the kernel +is in control on that CPU; when a CPU returns to user space the +specialized stacks contain no useful data. The main CPU stacks are: + +* Interrupt stack. IRQSTACKSIZE + + Used for external hardware interrupts. If this is the first external + hardware interrupt (i.e. not a nested hardware interrupt) then the + kernel switches from the current task to the interrupt stack. Like + the split thread and interrupt stacks on i386 (with CONFIG_4KSTACKS), + this gives more room for kernel interrupt processing without having + to increase the size of every per thread stack. + + The interrupt stack is also used when processing a softirq. + +Switching to the kernel interrupt stack is done by software based on a +per CPU interrupt nest counter. This is needed because x86-64 "IST" +hardware stacks cannot nest without races. + +x86_64 also has a feature which is not available on i386, the ability +to automatically switch to a new stack for designated events such as +double fault or NMI, which makes it easier to handle these unusual +events on x86_64. This feature is called the Interrupt Stack Table +(IST). There can be up to 7 IST entries per CPU. The IST code is an +index into the Task State Segment (TSS). The IST entries in the TSS +point to dedicated stacks; each stack can be a different size. + +An IST is selected by a non-zero value in the IST field of an +interrupt-gate descriptor. When an interrupt occurs and the hardware +loads such a descriptor, the hardware automatically sets the new stack +pointer based on the IST value, then invokes the interrupt handler. If +software wants to allow nested IST interrupts then the handler must +adjust the IST values on entry to and exit from the interrupt handler. +(This is occasionally done, e.g. for debug exceptions.) + +Events with different IST codes (i.e. with different stacks) can be +nested. For example, a debug interrupt can safely be interrupted by an +NMI. arch/x86_64/kernel/entry.S::paranoidentry adjusts the stack +pointers on entry to and exit from all IST events, in theory allowing +IST events with the same code to be nested. However in most cases, the +stack size allocated to an IST assumes no nesting for the same code. +If that assumption is ever broken then the stacks will become corrupt. + +The currently assigned IST stacks are :- + +* STACKFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). + + Used for interrupt 12 - Stack Fault Exception (#SS). + + This allows the CPU to recover from invalid stack segments. Rarely + happens. + +* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). + + Used for interrupt 8 - Double Fault Exception (#DF). + + Invoked when handling one exception causes another exception. Happens + when the kernel is very confused (e.g. kernel stack pointer corrupt). + Using a separate stack allows the kernel to recover from it well enough + in many cases to still output an oops. + +* NMI_STACK. EXCEPTION_STKSZ (PAGE_SIZE). + + Used for non-maskable interrupts (NMI). + + NMI can be delivered at any time, including when the kernel is in the + middle of switching stacks. Using IST for NMI events avoids making + assumptions about the previous state of the kernel stack. + +* DEBUG_STACK. DEBUG_STKSZ + + Used for hardware debug interrupts (interrupt 1) and for software + debug interrupts (INT3). + + When debugging a kernel, debug interrupts (both hardware and + software) can occur at any time. Using IST for these interrupts + avoids making assumptions about the previous state of the kernel + stack. + +* MCE_STACK. EXCEPTION_STKSZ (PAGE_SIZE). + + Used for interrupt 18 - Machine Check Exception (#MC). + + MCE can be delivered at any time, including when the kernel is in the + middle of switching stacks. Using IST for MCE events avoids making + assumptions about the previous state of the kernel stack. + +For more details see the Intel IA32 or AMD AMD64 architecture manuals. diff --git a/Documentation/x86/x86_64/machinecheck b/Documentation/x86/x86_64/machinecheck new file mode 100644 index 00000000000..a05e58e7b15 --- /dev/null +++ b/Documentation/x86/x86_64/machinecheck @@ -0,0 +1,77 @@ + +Configurable sysfs parameters for the x86-64 machine check code. + +Machine checks report internal hardware error conditions detected +by the CPU. Uncorrected errors typically cause a machine check +(often with panic), corrected ones cause a machine check log entry. + +Machine checks are organized in banks (normally associated with +a hardware subsystem) and subevents in a bank. The exact meaning +of the banks and subevent is CPU specific. + +mcelog knows how to decode them. + +When you see the "Machine check errors logged" message in the system +log then mcelog should run to collect and decode machine check entries +from /dev/mcelog. Normally mcelog should be run regularly from a cronjob. + +Each CPU has a directory in /sys/devices/system/machinecheck/machinecheckN +(N = CPU number) + +The directory contains some configurable entries: + +Entries: + +bankNctl +(N bank number) + 64bit Hex bitmask enabling/disabling specific subevents for bank N + When a bit in the bitmask is zero then the respective + subevent will not be reported. + By default all events are enabled. + Note that BIOS maintain another mask to disable specific events + per bank. This is not visible here + +The following entries appear for each CPU, but they are truly shared +between all CPUs. + +check_interval + How often to poll for corrected machine check errors, in seconds + (Note output is hexademical). Default 5 minutes. When the poller + finds MCEs it triggers an exponential speedup (poll more often) on + the polling interval. When the poller stops finding MCEs, it + triggers an exponential backoff (poll less often) on the polling + interval. The check_interval variable is both the initial and + maximum polling interval. + +tolerant + Tolerance level. When a machine check exception occurs for a non + corrected machine check the kernel can take different actions. + Since machine check exceptions can happen any time it is sometimes + risky for the kernel to kill a process because it defies + normal kernel locking rules. The tolerance level configures + how hard the kernel tries to recover even at some risk of + deadlock. Higher tolerant values trade potentially better uptime + with the risk of a crash or even corruption (for tolerant >= 3). + + 0: always panic on uncorrected errors, log corrected errors + 1: panic or SIGBUS on uncorrected errors, log corrected errors + 2: SIGBUS or log uncorrected errors, log corrected errors + 3: never panic or SIGBUS, log all errors (for testing only) + + Default: 1 + + Note this only makes a difference if the CPU allows recovery + from a machine check exception. Current x86 CPUs generally do not. + +trigger + Program to run when a machine check event is detected. + This is an alternative to running mcelog regularly from cron + and allows to detect events faster. + +TBD document entries for AMD threshold interrupt configuration + +For more details about the x86 machine check architecture +see the Intel and AMD architecture manuals from their developer websites. + +For more details about the architecture see +see http://one.firstfloor.org/~andi/mce.pdf diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt new file mode 100644 index 00000000000..b89b6d2bebf --- /dev/null +++ b/Documentation/x86/x86_64/mm.txt @@ -0,0 +1,29 @@ + + + +Virtual memory map with 4 level page tables: + +0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm +hole caused by [48:63] sign extension +ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole +ffff810000000000 - ffffc0ffffffffff (=46 bits) direct mapping of all phys. memory +ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole +ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space +ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB) +... unused hole ... +ffffffff80000000 - ffffffff82800000 (=40 MB) kernel text mapping, from phys 0 +... unused hole ... +ffffffff88000000 - fffffffffff00000 (=1919 MB) module mapping space + +The direct mapping covers all memory in the system up to the highest +memory address (this means in some cases it can also include PCI memory +holes). + +vmalloc space is lazily synchronized into the different PML4 pages of +the processes using the page fault handler, with init_level4_pgt as +reference. + +Current X86-64 implementations only support 40 bits of address space, +but we support up to 46 bits. This expands into MBZ space in the page tables. + +-Andi Kleen, Jul 2004 diff --git a/Documentation/x86/x86_64/uefi.txt b/Documentation/x86/x86_64/uefi.txt new file mode 100644 index 00000000000..7d77120a518 --- /dev/null +++ b/Documentation/x86/x86_64/uefi.txt @@ -0,0 +1,38 @@ +General note on [U]EFI x86_64 support +------------------------------------- + +The nomenclature EFI and UEFI are used interchangeably in this document. + +Although the tools below are _not_ needed for building the kernel, +the needed bootloader support and associated tools for x86_64 platforms +with EFI firmware and specifications are listed below. + +1. UEFI specification: http://www.uefi.org + +2. Booting Linux kernel on UEFI x86_64 platform requires bootloader + support. Elilo with x86_64 support can be used. + +3. x86_64 platform with EFI/UEFI firmware. + +Mechanics: +--------- +- Build the kernel with the following configuration. + CONFIG_FB_EFI=y + CONFIG_FRAMEBUFFER_CONSOLE=y + If EFI runtime services are expected, the following configuration should + be selected. + CONFIG_EFI=y + CONFIG_EFI_VARS=y or m # optional +- Create a VFAT partition on the disk +- Copy the following to the VFAT partition: + elilo bootloader with x86_64 support, elilo configuration file, + kernel image built in first step and corresponding + initrd. Instructions on building elilo and its dependencies + can be found in the elilo sourceforge project. +- Boot to EFI shell and invoke elilo choosing the kernel image built + in first step. +- If some or all EFI runtime services don't work, you can try following + kernel command line parameters to turn off some or all EFI runtime + services. + noefi turn off all EFI runtime services + reboot_type=k turn off EFI reboot runtime service diff --git a/Documentation/x86_64/00-INDEX b/Documentation/x86_64/00-INDEX deleted file mode 100644 index 92fc20ab5f0..00000000000 --- a/Documentation/x86_64/00-INDEX +++ /dev/null @@ -1,16 +0,0 @@ -00-INDEX - - This file -boot-options.txt - - AMD64-specific boot options. -cpu-hotplug-spec - - Firmware support for CPU hotplug under Linux/x86-64 -fake-numa-for-cpusets - - Using numa=fake and CPUSets for Resource Management -kernel-stacks - - Context-specific per-processor interrupt stacks. -machinecheck - - Configurable sysfs parameters for the x86-64 machine check code. -mm.txt - - Memory layout of x86-64 (4 level page tables, 46 bits physical). -uefi.txt - - Booting Linux via Unified Extensible Firmware Interface. diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt deleted file mode 100644 index b0c7b6c4abd..00000000000 --- a/Documentation/x86_64/boot-options.txt +++ /dev/null @@ -1,314 +0,0 @@ -AMD64 specific boot options - -There are many others (usually documented in driver documentation), but -only the AMD64 specific ones are listed here. - -Machine check - - mce=off disable machine check - mce=bootlog Enable logging of machine checks left over from booting. - Disabled by default on AMD because some BIOS leave bogus ones. - If your BIOS doesn't do that it's a good idea to enable though - to make sure you log even machine check events that result - in a reboot. On Intel systems it is enabled by default. - mce=nobootlog - Disable boot machine check logging. - mce=tolerancelevel (number) - 0: always panic on uncorrected errors, log corrected errors - 1: panic or SIGBUS on uncorrected errors, log corrected errors - 2: SIGBUS or log uncorrected errors, log corrected errors - 3: never panic or SIGBUS, log all errors (for testing only) - Default is 1 - Can be also set using sysfs which is preferable. - - nomce (for compatibility with i386): same as mce=off - - Everything else is in sysfs now. - -APICs - - apic Use IO-APIC. Default - - noapic Don't use the IO-APIC. - - disableapic Don't use the local APIC - - nolapic Don't use the local APIC (alias for i386 compatibility) - - pirq=... See Documentation/i386/IO-APIC.txt - - noapictimer Don't set up the APIC timer - - no_timer_check Don't check the IO-APIC timer. This can work around - problems with incorrect timer initialization on some boards. - - apicmaintimer Run time keeping from the local APIC timer instead - of using the PIT/HPET interrupt for this. This is useful - when the PIT/HPET interrupts are unreliable. - - noapicmaintimer Don't do time keeping using the APIC timer. - Useful when this option was auto selected, but doesn't work. - - apicpmtimer - Do APIC timer calibration using the pmtimer. Implies - apicmaintimer. Useful when your PIT timer is totally - broken. - - disable_8254_timer / enable_8254_timer - Enable interrupt 0 timer routing over the 8254 in addition to over - the IO-APIC. The kernel tries to set a sensible default. - -Early Console - - syntax: earlyprintk=vga - earlyprintk=serial[,ttySn[,baudrate]] - - The early console is useful when the kernel crashes before the - normal console is initialized. It is not enabled by - default because it has some cosmetic problems. - Append ,keep to not disable it when the real console takes over. - Only vga or serial at a time, not both. - Currently only ttyS0 and ttyS1 are supported. - Interaction with the standard serial driver is not very good. - The VGA output is eventually overwritten by the real console. - -Timing - - notsc - Don't use the CPU time stamp counter to read the wall time. - This can be used to work around timing problems on multiprocessor systems - with not properly synchronized CPUs. - - report_lost_ticks - Report when timer interrupts are lost because some code turned off - interrupts for too long. - - nmi_watchdog=NUMBER[,panic] - NUMBER can be: - 0 don't use an NMI watchdog - 1 use the IO-APIC timer for the NMI watchdog - 2 use the local APIC for the NMI watchdog using a performance counter. Note - This will use one performance counter and the local APIC's performance - vector. - When panic is specified panic when an NMI watchdog timeout occurs. - This is useful when you use a panic=... timeout and need the box - quickly up again. - - nohpet - Don't use the HPET timer. - -Idle loop - - idle=poll - Don't do power saving in the idle loop using HLT, but poll for rescheduling - event. This will make the CPUs eat a lot more power, but may be useful - to get slightly better performance in multiprocessor benchmarks. It also - makes some profiling using performance counters more accurate. - Please note that on systems with MONITOR/MWAIT support (like Intel EM64T - CPUs) this option has no performance advantage over the normal idle loop. - It may also interact badly with hyperthreading. - -Rebooting - - reboot=b[ios] | t[riple] | k[bd] | a[cpi] | e[fi] [, [w]arm | [c]old] - bios Use the CPU reboot vector for warm reset - warm Don't set the cold reboot flag - cold Set the cold reboot flag - triple Force a triple fault (init) - kbd Use the keyboard controller. cold reset (default) - acpi Use the ACPI RESET_REG in the FADT. If ACPI is not configured or the - ACPI reset does not work, the reboot path attempts the reset using - the keyboard controller. - efi Use efi reset_system runtime service. If EFI is not configured or the - EFI reset does not work, the reboot path attempts the reset using - the keyboard controller. - - Using warm reset will be much faster especially on big memory - systems because the BIOS will not go through the memory check. - Disadvantage is that not all hardware will be completely reinitialized - on reboot so there may be boot problems on some systems. - - reboot=force - - Don't stop other CPUs on reboot. This can make reboot more reliable - in some cases. - -Non Executable Mappings - - noexec=on|off - - on Enable(default) - off Disable - -SMP - - additional_cpus=NUM Allow NUM more CPUs for hotplug - (defaults are specified by the BIOS, see Documentation/x86_64/cpu-hotplug-spec) - -NUMA - - numa=off Only set up a single NUMA node spanning all memory. - - numa=noacpi Don't parse the SRAT table for NUMA setup - - numa=fake=CMDLINE - If a number, fakes CMDLINE nodes and ignores NUMA setup of the - actual machine. Otherwise, system memory is configured - depending on the sizes and coefficients listed. For example: - numa=fake=2*512,1024,4*256,*128 - gives two 512M nodes, a 1024M node, four 256M nodes, and the - rest split into 128M chunks. If the last character of CMDLINE - is a *, the remaining memory is divided up equally among its - coefficient: - numa=fake=2*512,2* - gives two 512M nodes and the rest split into two nodes. - Otherwise, the remaining system RAM is allocated to an - additional node. - - numa=hotadd=percent - Only allow hotadd memory to preallocate page structures upto - percent of already available memory. - numa=hotadd=0 will disable hotadd memory. - -ACPI - - acpi=off Don't enable ACPI - acpi=ht Use ACPI boot table parsing, but don't enable ACPI - interpreter - acpi=force Force ACPI on (currently not needed) - - acpi=strict Disable out of spec ACPI workarounds. - - acpi_sci={edge,level,high,low} Set up ACPI SCI interrupt. - - acpi=noirq Don't route interrupts - -PCI - - pci=off Don't use PCI - pci=conf1 Use conf1 access. - pci=conf2 Use conf2 access. - pci=rom Assign ROMs. - pci=assign-busses Assign busses - pci=irqmask=MASK Set PCI interrupt mask to MASK - pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says. - pci=noacpi Don't use ACPI to set up PCI interrupt routing. - -IOMMU (input/output memory management unit) - - Currently four x86-64 PCI-DMA mapping implementations exist: - - 1. : use no hardware/software IOMMU at all - (e.g. because you have < 3 GB memory). - Kernel boot message: "PCI-DMA: Disabling IOMMU" - - 2. : AMD GART based hardware IOMMU. - Kernel boot message: "PCI-DMA: using GART IOMMU" - - 3. : Software IOMMU implementation. Used - e.g. if there is no hardware IOMMU in the system and it is need because - you have >3GB memory or told the kernel to us it (iommu=soft)) - Kernel boot message: "PCI-DMA: Using software bounce buffering - for IO (SWIOTLB)" - - 4. : IBM Calgary hardware IOMMU. Used in IBM - pSeries and xSeries servers. This hardware IOMMU supports DMA address - mapping with memory protection, etc. - Kernel boot message: "PCI-DMA: Using Calgary IOMMU" - - iommu=[][,noagp][,off][,force][,noforce][,leak[=] - [,memaper[=]][,merge][,forcesac][,fullflush][,nomerge] - [,noaperture][,calgary] - - General iommu options: - off Don't initialize and use any kind of IOMMU. - noforce Don't force hardware IOMMU usage when it is not needed. - (default). - force Force the use of the hardware IOMMU even when it is - not actually needed (e.g. because < 3 GB memory). - soft Use software bounce buffering (SWIOTLB) (default for - Intel machines). This can be used to prevent the usage - of an available hardware IOMMU. - - iommu options only relevant to the AMD GART hardware IOMMU: - Set the size of the remapping area in bytes. - allowed Overwrite iommu off workarounds for specific chipsets. - fullflush Flush IOMMU on each allocation (default). - nofullflush Don't use IOMMU fullflush. - leak Turn on simple iommu leak tracing (only when - CONFIG_IOMMU_LEAK is on). Default number of leak pages - is 20. - memaper[=] Allocate an own aperture over RAM with size 32MB<4GB. - DAC is used with 32-bit PCI to push a 64-bit address in - two cycles. When off all DMA over >4GB is forced through - an IOMMU or software bounce buffering. - nodac Forbid DAC mode, i.e. DMA >4GB. - panic Always panic when IOMMU overflows. - calgary Use the Calgary IOMMU if it is available - - iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU - implementation: - swiotlb=[,force] - Prereserve that many 128K pages for the software IO - bounce buffering. - force Force all IO through the software TLB. - - Settings for the IBM Calgary hardware IOMMU currently found in IBM - pSeries and xSeries machines: - - calgary=[64k,128k,256k,512k,1M,2M,4M,8M] - calgary=[translate_empty_slots] - calgary=[disable=] - panic Always panic when IOMMU overflows - - 64k,...,8M - Set the size of each PCI slot's translation table - when using the Calgary IOMMU. This is the size of the translation - table itself in main memory. The smallest table, 64k, covers an IO - space of 32MB; the largest, 8MB table, can cover an IO space of - 4GB. Normally the kernel will make the right choice by itself. - - translate_empty_slots - Enable translation even on slots that have - no devices attached to them, in case a device will be hotplugged - in the future. - - disable= - Disable translation on a given PHB. For - example, the built-in graphics adapter resides on the first bridge - (PCI bus number 0); if translation (isolation) is enabled on this - bridge, X servers that access the hardware directly from user - space might stop working. Use this option if you have devices that - are accessed from userspace directly on some PCI host bridge. - -Debugging - - oops=panic Always panic on oopses. Default is to just kill the process, - but there is a small probability of deadlocking the machine. - This will also cause panics on machine check exceptions. - Useful together with panic=30 to trigger a reboot. - - kstack=N Print N words from the kernel stack in oops dumps. - - pagefaulttrace Dump all page faults. Only useful for extreme debugging - and will create a lot of output. - - call_trace=[old|both|newfallback|new] - old: use old inexact backtracer - new: use new exact dwarf2 unwinder - both: print entries from both - newfallback: use new unwinder but fall back to old if it gets - stuck (default) - -Miscellaneous - - nogbpages - Do not use GB pages for kernel direct mappings. - gbpages - Use GB pages for kernel direct mappings. diff --git a/Documentation/x86_64/cpu-hotplug-spec b/Documentation/x86_64/cpu-hotplug-spec deleted file mode 100644 index 3c23e0587db..00000000000 --- a/Documentation/x86_64/cpu-hotplug-spec +++ /dev/null @@ -1,21 +0,0 @@ -Firmware support for CPU hotplug under Linux/x86-64 ---------------------------------------------------- - -Linux/x86-64 supports CPU hotplug now. For various reasons Linux wants to -know in advance of boot time the maximum number of CPUs that could be plugged -into the system. ACPI 3.0 currently has no official way to supply -this information from the firmware to the operating system. - -In ACPI each CPU needs an LAPIC object in the MADT table (5.2.11.5 in the -ACPI 3.0 specification). ACPI already has the concept of disabled LAPIC -objects by setting the Enabled bit in the LAPIC object to zero. - -For CPU hotplug Linux/x86-64 expects now that any possible future hotpluggable -CPU is already available in the MADT. If the CPU is not available yet -it should have its LAPIC Enabled bit set to 0. Linux will use the number -of disabled LAPICs to compute the maximum number of future CPUs. - -In the worst case the user can overwrite this choice using a command line -option (additional_cpus=...), but it is recommended to supply the correct -number (or a reasonable approximation of it, with erring towards more not less) -in the MADT to avoid manual configuration. diff --git a/Documentation/x86_64/fake-numa-for-cpusets b/Documentation/x86_64/fake-numa-for-cpusets deleted file mode 100644 index d1a985c5b00..00000000000 --- a/Documentation/x86_64/fake-numa-for-cpusets +++ /dev/null @@ -1,66 +0,0 @@ -Using numa=fake and CPUSets for Resource Management -Written by David Rientjes - -This document describes how the numa=fake x86_64 command-line option can be used -in conjunction with cpusets for coarse memory management. Using this feature, -you can create fake NUMA nodes that represent contiguous chunks of memory and -assign them to cpusets and their attached tasks. This is a way of limiting the -amount of system memory that are available to a certain class of tasks. - -For more information on the features of cpusets, see Documentation/cpusets.txt. -There are a number of different configurations you can use for your needs. For -more information on the numa=fake command line option and its various ways of -configuring fake nodes, see Documentation/x86_64/boot-options.txt. - -For the purposes of this introduction, we'll assume a very primitive NUMA -emulation setup of "numa=fake=4*512,". This will split our system memory into -four equal chunks of 512M each that we can now use to assign to cpusets. As -you become more familiar with using this combination for resource control, -you'll determine a better setup to minimize the number of nodes you have to deal -with. - -A machine may be split as follows with "numa=fake=4*512," as reported by dmesg: - - Faking node 0 at 0000000000000000-0000000020000000 (512MB) - Faking node 1 at 0000000020000000-0000000040000000 (512MB) - Faking node 2 at 0000000040000000-0000000060000000 (512MB) - Faking node 3 at 0000000060000000-0000000080000000 (512MB) - ... - On node 0 totalpages: 130975 - On node 1 totalpages: 131072 - On node 2 totalpages: 131072 - On node 3 totalpages: 131072 - -Now following the instructions for mounting the cpusets filesystem from -Documentation/cpusets.txt, you can assign fake nodes (i.e. contiguous memory -address spaces) to individual cpusets: - - [root@xroads /]# mkdir exampleset - [root@xroads /]# mount -t cpuset none exampleset - [root@xroads /]# mkdir exampleset/ddset - [root@xroads /]# cd exampleset/ddset - [root@xroads /exampleset/ddset]# echo 0-1 > cpus - [root@xroads /exampleset/ddset]# echo 0-1 > mems - -Now this cpuset, 'ddset', will only allowed access to fake nodes 0 and 1 for -memory allocations (1G). - -You can now assign tasks to these cpusets to limit the memory resources -available to them according to the fake nodes assigned as mems: - - [root@xroads /exampleset/ddset]# echo $$ > tasks - [root@xroads /exampleset/ddset]# dd if=/dev/zero of=tmp bs=1024 count=1G - [1] 13425 - -Notice the difference between the system memory usage as reported by -/proc/meminfo between the restricted cpuset case above and the unrestricted -case (i.e. running the same 'dd' command without assigning it to a fake NUMA -cpuset): - Unrestricted Restricted - MemTotal: 3091900 kB 3091900 kB - MemFree: 42113 kB 1513236 kB - -This allows for coarse memory management for the tasks you assign to particular -cpusets. Since cpusets can form a hierarchy, you can create some pretty -interesting combinations of use-cases for various classes of tasks for your -memory management needs. diff --git a/Documentation/x86_64/kernel-stacks b/Documentation/x86_64/kernel-stacks deleted file mode 100644 index 5ad65d51fb9..00000000000 --- a/Documentation/x86_64/kernel-stacks +++ /dev/null @@ -1,99 +0,0 @@ -Most of the text from Keith Owens, hacked by AK - -x86_64 page size (PAGE_SIZE) is 4K. - -Like all other architectures, x86_64 has a kernel stack for every -active thread. These thread stacks are THREAD_SIZE (2*PAGE_SIZE) big. -These stacks contain useful data as long as a thread is alive or a -zombie. While the thread is in user space the kernel stack is empty -except for the thread_info structure at the bottom. - -In addition to the per thread stacks, there are specialized stacks -associated with each CPU. These stacks are only used while the kernel -is in control on that CPU; when a CPU returns to user space the -specialized stacks contain no useful data. The main CPU stacks are: - -* Interrupt stack. IRQSTACKSIZE - - Used for external hardware interrupts. If this is the first external - hardware interrupt (i.e. not a nested hardware interrupt) then the - kernel switches from the current task to the interrupt stack. Like - the split thread and interrupt stacks on i386 (with CONFIG_4KSTACKS), - this gives more room for kernel interrupt processing without having - to increase the size of every per thread stack. - - The interrupt stack is also used when processing a softirq. - -Switching to the kernel interrupt stack is done by software based on a -per CPU interrupt nest counter. This is needed because x86-64 "IST" -hardware stacks cannot nest without races. - -x86_64 also has a feature which is not available on i386, the ability -to automatically switch to a new stack for designated events such as -double fault or NMI, which makes it easier to handle these unusual -events on x86_64. This feature is called the Interrupt Stack Table -(IST). There can be up to 7 IST entries per CPU. The IST code is an -index into the Task State Segment (TSS). The IST entries in the TSS -point to dedicated stacks; each stack can be a different size. - -An IST is selected by a non-zero value in the IST field of an -interrupt-gate descriptor. When an interrupt occurs and the hardware -loads such a descriptor, the hardware automatically sets the new stack -pointer based on the IST value, then invokes the interrupt handler. If -software wants to allow nested IST interrupts then the handler must -adjust the IST values on entry to and exit from the interrupt handler. -(This is occasionally done, e.g. for debug exceptions.) - -Events with different IST codes (i.e. with different stacks) can be -nested. For example, a debug interrupt can safely be interrupted by an -NMI. arch/x86_64/kernel/entry.S::paranoidentry adjusts the stack -pointers on entry to and exit from all IST events, in theory allowing -IST events with the same code to be nested. However in most cases, the -stack size allocated to an IST assumes no nesting for the same code. -If that assumption is ever broken then the stacks will become corrupt. - -The currently assigned IST stacks are :- - -* STACKFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). - - Used for interrupt 12 - Stack Fault Exception (#SS). - - This allows the CPU to recover from invalid stack segments. Rarely - happens. - -* DOUBLEFAULT_STACK. EXCEPTION_STKSZ (PAGE_SIZE). - - Used for interrupt 8 - Double Fault Exception (#DF). - - Invoked when handling one exception causes another exception. Happens - when the kernel is very confused (e.g. kernel stack pointer corrupt). - Using a separate stack allows the kernel to recover from it well enough - in many cases to still output an oops. - -* NMI_STACK. EXCEPTION_STKSZ (PAGE_SIZE). - - Used for non-maskable interrupts (NMI). - - NMI can be delivered at any time, including when the kernel is in the - middle of switching stacks. Using IST for NMI events avoids making - assumptions about the previous state of the kernel stack. - -* DEBUG_STACK. DEBUG_STKSZ - - Used for hardware debug interrupts (interrupt 1) and for software - debug interrupts (INT3). - - When debugging a kernel, debug interrupts (both hardware and - software) can occur at any time. Using IST for these interrupts - avoids making assumptions about the previous state of the kernel - stack. - -* MCE_STACK. EXCEPTION_STKSZ (PAGE_SIZE). - - Used for interrupt 18 - Machine Check Exception (#MC). - - MCE can be delivered at any time, including when the kernel is in the - middle of switching stacks. Using IST for MCE events avoids making - assumptions about the previous state of the kernel stack. - -For more details see the Intel IA32 or AMD AMD64 architecture manuals. diff --git a/Documentation/x86_64/machinecheck b/Documentation/x86_64/machinecheck deleted file mode 100644 index a05e58e7b15..00000000000 --- a/Documentation/x86_64/machinecheck +++ /dev/null @@ -1,77 +0,0 @@ - -Configurable sysfs parameters for the x86-64 machine check code. - -Machine checks report internal hardware error conditions detected -by the CPU. Uncorrected errors typically cause a machine check -(often with panic), corrected ones cause a machine check log entry. - -Machine checks are organized in banks (normally associated with -a hardware subsystem) and subevents in a bank. The exact meaning -of the banks and subevent is CPU specific. - -mcelog knows how to decode them. - -When you see the "Machine check errors logged" message in the system -log then mcelog should run to collect and decode machine check entries -from /dev/mcelog. Normally mcelog should be run regularly from a cronjob. - -Each CPU has a directory in /sys/devices/system/machinecheck/machinecheckN -(N = CPU number) - -The directory contains some configurable entries: - -Entries: - -bankNctl -(N bank number) - 64bit Hex bitmask enabling/disabling specific subevents for bank N - When a bit in the bitmask is zero then the respective - subevent will not be reported. - By default all events are enabled. - Note that BIOS maintain another mask to disable specific events - per bank. This is not visible here - -The following entries appear for each CPU, but they are truly shared -between all CPUs. - -check_interval - How often to poll for corrected machine check errors, in seconds - (Note output is hexademical). Default 5 minutes. When the poller - finds MCEs it triggers an exponential speedup (poll more often) on - the polling interval. When the poller stops finding MCEs, it - triggers an exponential backoff (poll less often) on the polling - interval. The check_interval variable is both the initial and - maximum polling interval. - -tolerant - Tolerance level. When a machine check exception occurs for a non - corrected machine check the kernel can take different actions. - Since machine check exceptions can happen any time it is sometimes - risky for the kernel to kill a process because it defies - normal kernel locking rules. The tolerance level configures - how hard the kernel tries to recover even at some risk of - deadlock. Higher tolerant values trade potentially better uptime - with the risk of a crash or even corruption (for tolerant >= 3). - - 0: always panic on uncorrected errors, log corrected errors - 1: panic or SIGBUS on uncorrected errors, log corrected errors - 2: SIGBUS or log uncorrected errors, log corrected errors - 3: never panic or SIGBUS, log all errors (for testing only) - - Default: 1 - - Note this only makes a difference if the CPU allows recovery - from a machine check exception. Current x86 CPUs generally do not. - -trigger - Program to run when a machine check event is detected. - This is an alternative to running mcelog regularly from cron - and allows to detect events faster. - -TBD document entries for AMD threshold interrupt configuration - -For more details about the x86 machine check architecture -see the Intel and AMD architecture manuals from their developer websites. - -For more details about the architecture see -see http://one.firstfloor.org/~andi/mce.pdf diff --git a/Documentation/x86_64/mm.txt b/Documentation/x86_64/mm.txt deleted file mode 100644 index b89b6d2bebf..00000000000 --- a/Documentation/x86_64/mm.txt +++ /dev/null @@ -1,29 +0,0 @@ - - - -Virtual memory map with 4 level page tables: - -0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm -hole caused by [48:63] sign extension -ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole -ffff810000000000 - ffffc0ffffffffff (=46 bits) direct mapping of all phys. memory -ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole -ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space -ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB) -... unused hole ... -ffffffff80000000 - ffffffff82800000 (=40 MB) kernel text mapping, from phys 0 -... unused hole ... -ffffffff88000000 - fffffffffff00000 (=1919 MB) module mapping space - -The direct mapping covers all memory in the system up to the highest -memory address (this means in some cases it can also include PCI memory -holes). - -vmalloc space is lazily synchronized into the different PML4 pages of -the processes using the page fault handler, with init_level4_pgt as -reference. - -Current X86-64 implementations only support 40 bits of address space, -but we support up to 46 bits. This expands into MBZ space in the page tables. - --Andi Kleen, Jul 2004 diff --git a/Documentation/x86_64/uefi.txt b/Documentation/x86_64/uefi.txt deleted file mode 100644 index 7d77120a518..00000000000 --- a/Documentation/x86_64/uefi.txt +++ /dev/null @@ -1,38 +0,0 @@ -General note on [U]EFI x86_64 support -------------------------------------- - -The nomenclature EFI and UEFI are used interchangeably in this document. - -Although the tools below are _not_ needed for building the kernel, -the needed bootloader support and associated tools for x86_64 platforms -with EFI firmware and specifications are listed below. - -1. UEFI specification: http://www.uefi.org - -2. Booting Linux kernel on UEFI x86_64 platform requires bootloader - support. Elilo with x86_64 support can be used. - -3. x86_64 platform with EFI/UEFI firmware. - -Mechanics: ---------- -- Build the kernel with the following configuration. - CONFIG_FB_EFI=y - CONFIG_FRAMEBUFFER_CONSOLE=y - If EFI runtime services are expected, the following configuration should - be selected. - CONFIG_EFI=y - CONFIG_EFI_VARS=y or m # optional -- Create a VFAT partition on the disk -- Copy the following to the VFAT partition: - elilo bootloader with x86_64 support, elilo configuration file, - kernel image built in first step and corresponding - initrd. Instructions on building elilo and its dependencies - can be found in the elilo sourceforge project. -- Boot to EFI shell and invoke elilo choosing the kernel image built - in first step. -- If some or all EFI runtime services don't work, you can try following - kernel command line parameters to turn off some or all EFI runtime - services. - noefi turn off all EFI runtime services - reboot_type=k turn off EFI reboot runtime service -- cgit v1.2.3