diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 2 | ||||
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 622 | ||||
| -rw-r--r-- | Documentation/powerpc/phyp-assisted-dump.txt | 127 |
3 files changed, 728 insertions, 23 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f4839606988..dfb5bef2401 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -954,6 +954,8 @@ and is between 256 and 4096 characters. It is defined in the file l2cr= [PPC] + l3cr= [PPC] + lapic [X86-32,APIC] Enable the local APIC even if BIOS disabled it. diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index 7b4e8a70882..4cc780024e6 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -59,12 +59,39 @@ Table of Contents p) Freescale Synchronous Serial Interface q) USB EHCI controllers - VII - Specifying interrupt information for devices + VII - Marvell Discovery mv64[345]6x System Controller chips + 1) The /system-controller node + 2) Child nodes of /system-controller + a) Marvell Discovery MDIO bus + b) Marvell Discovery ethernet controller + c) Marvell Discovery PHY nodes + d) Marvell Discovery SDMA nodes + e) Marvell Discovery BRG nodes + f) Marvell Discovery CUNIT nodes + g) Marvell Discovery MPSCROUTING nodes + h) Marvell Discovery MPSCINTR nodes + i) Marvell Discovery MPSC nodes + j) Marvell Discovery Watch Dog Timer nodes + k) Marvell Discovery I2C nodes + l) Marvell Discovery PIC (Programmable Interrupt Controller) nodes + m) Marvell Discovery MPP (Multipurpose Pins) multiplexing nodes + n) Marvell Discovery GPP (General Purpose Pins) nodes + o) Marvell Discovery PCI host bridge node + p) Marvell Discovery CPU Error nodes + q) Marvell Discovery SRAM Controller nodes + r) Marvell Discovery PCI Error Handler nodes + s) Marvell Discovery Memory Controller nodes + + VIII - Specifying interrupt information for devices 1) interrupts property 2) interrupt-parent property 3) OpenPIC Interrupt Controllers 4) ISA Interrupt Controllers + VIII - Specifying GPIO information for devices + 1) gpios property + 2) gpio-controller nodes + Appendix A - Sample SOC node for MPC8540 @@ -1269,10 +1296,6 @@ platforms are moved over to use the flattened-device-tree model. Recommended properties: - - linux,network-index : This is the intended "index" of this - network device. This is used by the bootwrapper to interpret - MAC addresses passed by the firmware when no information other - than indices is available to associate an address with a device. - phy-connection-type : a string naming the controller/PHY interface type, i.e., "mii" (default), "rmii", "gmii", "rgmii", "rgmii-id", "sgmii", "tbi", or "rtbi". This property is only really needed if the connection @@ -1622,8 +1645,7 @@ platforms are moved over to use the flattened-device-tree model. - device_type : should be "network", "hldc", "uart", "transparent" "bisync", "atm", or "serial". - compatible : could be "ucc_geth" or "fsl_atm" and so on. - - model : should be "UCC". - - device-id : the ucc number(1-8), corresponding to UCCx in UM. + - cell-index : the ucc number(1-8), corresponding to UCCx in UM. - reg : Offset and length of the register set for the device - interrupts : <a b> where a is the interrupt number and b is a field that represents an encoding of the sense and level @@ -1667,10 +1689,6 @@ platforms are moved over to use the flattened-device-tree model. - phy-handle : The phandle for the PHY connected to this controller. Recommended properties: - - linux,network-index : This is the intended "index" of this - network device. This is used by the bootwrapper to interpret - MAC addresses passed by the firmware when no information other - than indices is available to associate an address with a device. - phy-connection-type : a string naming the controller/PHY interface type, i.e., "mii" (default), "rmii", "gmii", "rgmii", "rgmii-id" (Internal Delay), "rgmii-txid" (delay on TX only), "rgmii-rxid" (delay on RX only), @@ -1680,8 +1698,7 @@ platforms are moved over to use the flattened-device-tree model. ucc@2000 { device_type = "network"; compatible = "ucc_geth"; - model = "UCC"; - device-id = <1>; + cell-index = <1>; reg = <2000 200>; interrupts = <a0 0>; interrupt-parent = <700>; @@ -1995,7 +2012,6 @@ platforms are moved over to use the flattened-device-tree model. interrupts = <20 8>; interrupt-parent = <&PIC>; phy-handle = <&PHY0>; - linux,network-index = <0>; fsl,cpm-command = <12000300>; }; @@ -2217,12 +2233,6 @@ platforms are moved over to use the flattened-device-tree model. EMAC, that is the content of the current (bogus) "phy-port" property. - Recommended properties: - - linux,network-index : This is the intended "index" of this - network device. This is used by the bootwrapper to interpret - MAC addresses passed by the firmware when no information other - than indices is available to associate an address with a device. - Optional properties: - phy-address : 1 cell, optional, MDIO address of the PHY. If absent, a search is performed. @@ -2246,7 +2256,6 @@ platforms are moved over to use the flattened-device-tree model. Example: EMAC0: ethernet@40000800 { - linux,network-index = <0>; device_type = "network"; compatible = "ibm,emac-440gp", "ibm,emac"; interrupt-parent = <&UIC1>; @@ -2817,9 +2826,528 @@ platforms are moved over to use the flattened-device-tree model. }; - More devices will be defined as this spec matures. +VII - Marvell Discovery mv64[345]6x System Controller chips +=========================================================== + +The Marvell mv64[345]60 series of system controller chips contain +many of the peripherals needed to implement a complete computer +system. In this section, we define device tree nodes to describe +the system controller chip itself and each of the peripherals +which it contains. Compatible string values for each node are +prefixed with the string "marvell,", for Marvell Technology Group Ltd. + +1) The /system-controller node + + This node is used to represent the system-controller and must be + present when the system uses a system contller chip. The top-level + system-controller node contains information that is global to all + devices within the system controller chip. The node name begins + with "system-controller" followed by the unit address, which is + the base address of the memory-mapped register set for the system + controller chip. + + Required properties: + + - ranges : Describes the translation of system controller addresses + for memory mapped registers. + - clock-frequency: Contains the main clock frequency for the system + controller chip. + - reg : This property defines the address and size of the + memory-mapped registers contained within the system controller + chip. The address specified in the "reg" property should match + the unit address of the system-controller node. + - #address-cells : Address representation for system controller + devices. This field represents the number of cells needed to + represent the address of the memory-mapped registers of devices + within the system controller chip. + - #size-cells : Size representation for for the memory-mapped + registers within the system controller chip. + - #interrupt-cells : Defines the width of cells used to represent + interrupts. + + Optional properties: + + - model : The specific model of the system controller chip. Such + as, "mv64360", "mv64460", or "mv64560". + - compatible : A string identifying the compatibility identifiers + of the system controller chip. + + The system-controller node contains child nodes for each system + controller device that the platform uses. Nodes should not be created + for devices which exist on the system controller chip but are not used + + Example Marvell Discovery mv64360 system-controller node: + + system-controller@f1000000 { /* Marvell Discovery mv64360 */ + #address-cells = <1>; + #size-cells = <1>; + model = "mv64360"; /* Default */ + compatible = "marvell,mv64360"; + clock-frequency = <133333333>; + reg = <0xf1000000 0x10000>; + virtual-reg = <0xf1000000>; + ranges = <0x88000000 0x88000000 0x1000000 /* PCI 0 I/O Space */ + 0x80000000 0x80000000 0x8000000 /* PCI 0 MEM Space */ + 0xa0000000 0xa0000000 0x4000000 /* User FLASH */ + 0x00000000 0xf1000000 0x0010000 /* Bridge's regs */ + 0xf2000000 0xf2000000 0x0040000>;/* Integrated SRAM */ + + [ child node definitions... ] + } + +2) Child nodes of /system-controller + + a) Marvell Discovery MDIO bus + + The MDIO is a bus to which the PHY devices are connected. For each + device that exists on this bus, a child node should be created. See + the definition of the PHY node below for an example of how to define + a PHY. + + Required properties: + - #address-cells : Should be <1> + - #size-cells : Should be <0> + - device_type : Should be "mdio" + - compatible : Should be "marvell,mv64360-mdio" + + Example: + + mdio { + #address-cells = <1>; + #size-cells = <0>; + device_type = "mdio"; + compatible = "marvell,mv64360-mdio"; + + ethernet-phy@0 { + ...... + }; + }; + + + b) Marvell Discovery ethernet controller + + The Discover ethernet controller is described with two levels + of nodes. The first level describes an ethernet silicon block + and the second level describes up to 3 ethernet nodes within + that block. The reason for the multiple levels is that the + registers for the node are interleaved within a single set + of registers. The "ethernet-block" level describes the + shared register set, and the "ethernet" nodes describe ethernet + port-specific properties. + + Ethernet block node + + Required properties: + - #address-cells : <1> + - #size-cells : <0> + - compatible : "marvell,mv64360-eth-block" + - reg : Offset and length of the register set for this block + + Example Discovery Ethernet block node: + ethernet-block@2000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "marvell,mv64360-eth-block"; + reg = <0x2000 0x2000>; + ethernet@0 { + ....... + }; + }; + + Ethernet port node + + Required properties: + - device_type : Should be "network". + - compatible : Should be "marvell,mv64360-eth". + - reg : Should be <0>, <1>, or <2>, according to which registers + within the silicon block the device uses. + - interrupts : <a> where a is the interrupt number for the port. + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + - phy : the phandle for the PHY connected to this ethernet + controller. + - local-mac-address : 6 bytes, MAC address + + Example Discovery Ethernet port node: + ethernet@0 { + device_type = "network"; + compatible = "marvell,mv64360-eth"; + reg = <0>; + interrupts = <32>; + interrupt-parent = <&PIC>; + phy = <&PHY0>; + local-mac-address = [ 00 00 00 00 00 00 ]; + }; + + + + c) Marvell Discovery PHY nodes + + Required properties: + - device_type : Should be "ethernet-phy" + - interrupts : <a> where a is the interrupt number for this phy. + - interrupt-parent : the phandle for the interrupt controller that + services interrupts for this device. + - reg : The ID number for the phy, usually a small integer + + Example Discovery PHY node: + ethernet-phy@1 { + device_type = "ethernet-phy"; + compatible = "broadcom,bcm5421"; + interrupts = <76>; /* GPP 12 */ + interrupt-parent = <&PIC>; + reg = <1>; + }; + + + d) Marvell Discovery SDMA nodes + + Represent DMA hardware associated with the MPSC (multiprotocol + serial controllers). + + Required properties: + - compatible : "marvell,mv64360-sdma" + - reg : Offset and length of the register set for this device + - interrupts : <a> where a is the interrupt number for the DMA + device. + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery SDMA node: + sdma@4000 { + compatible = "marvell,mv64360-sdma"; + reg = <0x4000 0xc18>; + virtual-reg = <0xf1004000>; + interrupts = <36>; + interrupt-parent = <&PIC>; + }; + + + e) Marvell Discovery BRG nodes + + Represent baud rate generator hardware associated with the MPSC + (multiprotocol serial controllers). + + Required properties: + - compatible : "marvell,mv64360-brg" + - reg : Offset and length of the register set for this device + - clock-src : A value from 0 to 15 which selects the clock + source for the baud rate generator. This value corresponds + to the CLKS value in the BRGx configuration register. See + the mv64x60 User's Manual. + - clock-frequence : The frequency (in Hz) of the baud rate + generator's input clock. + - current-speed : The current speed setting (presumably by + firmware) of the baud rate generator. + + Example Discovery BRG node: + brg@b200 { + compatible = "marvell,mv64360-brg"; + reg = <0xb200 0x8>; + clock-src = <8>; + clock-frequency = <133333333>; + current-speed = <9600>; + }; + + + f) Marvell Discovery CUNIT nodes + + Represent the Serial Communications Unit device hardware. + + Required properties: + - reg : Offset and length of the register set for this device + + Example Discovery CUNIT node: + cunit@f200 { + reg = <0xf200 0x200>; + }; + + + g) Marvell Discovery MPSCROUTING nodes + + Represent the Discovery's MPSC routing hardware + + Required properties: + - reg : Offset and length of the register set for this device + + Example Discovery CUNIT node: + mpscrouting@b500 { + reg = <0xb400 0xc>; + }; + + + h) Marvell Discovery MPSCINTR nodes + + Represent the Discovery's MPSC DMA interrupt hardware registers + (SDMA cause and mask registers). + + Required properties: + - reg : Offset and length of the register set for this device -VII - Specifying interrupt information for devices + Example Discovery MPSCINTR node: + mpsintr@b800 { + reg = <0xb800 0x100>; + }; + + + i) Marvell Discovery MPSC nodes + + Represent the Discovery's MPSC (Multiprotocol Serial Controller) + serial port. + + Required properties: + - device_type : "serial" + - compatible : "marvell,mv64360-mpsc" + - reg : Offset and length of the register set for this device + - sdma : the phandle for the SDMA node used by this port + - brg : the phandle for the BRG node used by this port + - cunit : the phandle for the CUNIT node used by this port + - mpscrouting : the phandle for the MPSCROUTING node used by this port + - mpscintr : the phandle for the MPSCINTR node used by this port + - cell-index : the hardware index of this cell in the MPSC core + - max_idle : value needed for MPSC CHR3 (Maximum Frame Length) + register + - interrupts : <a> where a is the interrupt number for the MPSC. + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery MPSCINTR node: + mpsc@8000 { + device_type = "serial"; + compatible = "marvell,mv64360-mpsc"; + reg = <0x8000 0x38>; + virtual-reg = <0xf1008000>; + sdma = <&SDMA0>; + brg = <&BRG0>; + cunit = <&CUNIT>; + mpscrouting = <&MPSCROUTING>; + mpscintr = <&MPSCINTR>; + cell-index = <0>; + max_idle = <40>; + interrupts = <40>; + interrupt-parent = <&PIC>; + }; + + + j) Marvell Discovery Watch Dog Timer nodes + + Represent the Discovery's watchdog timer hardware + + Required properties: + - compatible : "marvell,mv64360-wdt" + - reg : Offset and length of the register set for this device + + Example Discovery Watch Dog Timer node: + wdt@b410 { + compatible = "marvell,mv64360-wdt"; + reg = <0xb410 0x8>; + }; + + + k) Marvell Discovery I2C nodes + + Represent the Discovery's I2C hardware + + Required properties: + - device_type : "i2c" + - compatible : "marvell,mv64360-i2c" + - reg : Offset and length of the register set for this device + - interrupts : <a> where a is the interrupt number for the I2C. + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery I2C node: + compatible = "marvell,mv64360-i2c"; + reg = <0xc000 0x20>; + virtual-reg = <0xf100c000>; + interrupts = <37>; + interrupt-parent = <&PIC>; + }; + + + l) Marvell Discovery PIC (Programmable Interrupt Controller) nodes + + Represent the Discovery's PIC hardware + + Required properties: + - #interrupt-cells : <1> + - #address-cells : <0> + - compatible : "marvell,mv64360-pic" + - reg : Offset and length of the register set for this device + - interrupt-controller + + Example Discovery PIC node: + pic { + #interrupt-cells = <1>; + #address-cells = <0>; + compatible = "marvell,mv64360-pic"; + reg = <0x0 0x88>; + interrupt-controller; + }; + + + m) Marvell Discovery MPP (Multipurpose Pins) multiplexing nodes + + Represent the Discovery's MPP hardware + + Required properties: + - compatible : "marvell,mv64360-mpp" + - reg : Offset and length of the register set for this device + + Example Discovery MPP node: + mpp@f000 { + compatible = "marvell,mv64360-mpp"; + reg = <0xf000 0x10>; + }; + + + n) Marvell Discovery GPP (General Purpose Pins) nodes + + Represent the Discovery's GPP hardware + + Required properties: + - compatible : "marvell,mv64360-gpp" + - reg : Offset and length of the register set for this device + + Example Discovery GPP node: + gpp@f000 { + compatible = "marvell,mv64360-gpp"; + reg = <0xf100 0x20>; + }; + + + o) Marvell Discovery PCI host bridge node + + Represents the Discovery's PCI host bridge device. The properties + for this node conform to Rev 2.1 of the PCI Bus Binding to IEEE + 1275-1994. A typical value for the compatible property is + "marvell,mv64360-pci". + + Example Discovery PCI host bridge node + pci@80000000 { + #address-cells = <3>; + #size-cells = <2>; + #interrupt-cells = <1>; + device_type = "pci"; + compatible = "marvell,mv64360-pci"; + reg = <0xcf8 0x8>; + ranges = <0x01000000 0x0 0x0 + 0x88000000 0x0 0x01000000 + 0x02000000 0x0 0x80000000 + 0x80000000 0x0 0x08000000>; + bus-range = <0 255>; + clock-frequency = <66000000>; + interrupt-parent = <&PIC>; + interrupt-map-mask = <0xf800 0x0 0x0 0x7>; + interrupt-map = < + /* IDSEL 0x0a */ + 0x5000 0 0 1 &PIC 80 + 0x5000 0 0 2 &PIC 81 + 0x5000 0 0 3 &PIC 91 + 0x5000 0 0 4 &PIC 93 + + /* IDSEL 0x0b */ + 0x5800 0 0 1 &PIC 91 + 0x5800 0 0 2 &PIC 93 + 0x5800 0 0 3 &PIC 80 + 0x5800 0 0 4 &PIC 81 + + /* IDSEL 0x0c */ + 0x6000 0 0 1 &PIC 91 + 0x6000 0 0 2 &PIC 93 + 0x6000 0 0 3 &PIC 80 + 0x6000 0 0 4 &PIC 81 + + /* IDSEL 0x0d */ + 0x6800 0 0 1 &PIC 93 + 0x6800 0 0 2 &PIC 80 + 0x6800 0 0 3 &PIC 81 + 0x6800 0 0 4 &PIC 91 + >; + }; + + + p) Marvell Discovery CPU Error nodes + + Represent the Discovery's CPU error handler device. + + Required properties: + - compatible : "marvell,mv64360-cpu-error" + - reg : Offset and length of the register set for this device + - interrupts : the interrupt number for this device + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery CPU Error node: + cpu-error@0070 { + compatible = "marvell,mv64360-cpu-error"; + reg = <0x70 0x10 0x128 0x28>; + interrupts = <3>; + interrupt-parent = <&PIC>; + }; + + + q) Marvell Discovery SRAM Controller nodes + + Represent the Discovery's SRAM controller device. + + Required properties: + - compatible : "marvell,mv64360-sram-ctrl" + - reg : Offset and length of the register set for this device + - interrupts : the interrupt number for this device + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery SRAM Controller node: + sram-ctrl@0380 { + compatible = "marvell,mv64360-sram-ctrl"; + reg = <0x380 0x80>; + interrupts = <13>; + interrupt-parent = <&PIC>; + }; + + + r) Marvell Discovery PCI Error Handler nodes + + Represent the Discovery's PCI error handler device. + + Required properties: + - compatible : "marvell,mv64360-pci-error" + - reg : Offset and length of the register set for this device + - interrupts : the interrupt number for this device + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery PCI Error Handler node: + pci-error@1d40 { + compatible = "marvell,mv64360-pci-error"; + reg = <0x1d40 0x40 0xc28 0x4>; + interrupts = <12>; + interrupt-parent = <&PIC>; + }; + + + s) Marvell Discovery Memory Controller nodes + + Represent the Discovery's memory controller device. + + Required properties: + - compatible : "marvell,mv64360-mem-ctrl" + - reg : Offset and length of the register set for this device + - interrupts : the interrupt number for this device + - interrupt-parent : the phandle for the interrupt controller + that services interrupts for this device. + + Example Discovery Memory Controller node: + mem-ctrl@1400 { + compatible = "marvell,mv64360-mem-ctrl"; + reg = <0x1400 0x60>; + interrupts = <17>; + interrupt-parent = <&PIC>; + }; + + +VIII - Specifying interrupt information for devices =================================================== The device tree represents the busses and devices of a hardware @@ -2905,6 +3433,54 @@ encodings listed below: 2 = high to low edge sensitive type enabled 3 = low to high edge sensitive type enabled +VIII - Specifying GPIO information for devices +============================================== + +1) gpios property +----------------- + +Nodes that makes use of GPIOs should define them using `gpios' property, +format of which is: <&gpio-controller1-phandle gpio1-specifier + &gpio-controller2-phandle gpio2-specifier + 0 /* holes are permitted, means no GPIO 3 */ + &gpio-controller4-phandle gpio4-specifier + ...>; + +Note that gpio-specifier length is controller dependent. + +gpio-specifier may encode: bank, pin position inside the bank, +whether pin is open-drain and whether pin is logically inverted. + +Example of the node using GPIOs: + + node { + gpios = <&qe_pio_e 18 0>; + }; + +In this example gpio-specifier is "18 0" and encodes GPIO pin number, +and empty GPIO flags as accepted by the "qe_pio_e" gpio-controller. + +2) gpio-controller nodes +------------------------ + +Every GPIO controller node must have #gpio-cells property defined, +this information will be used to translate gpio-specifiers. + +Example of two SOC GPIO banks defined as gpio-controller nodes: + + qe_pio_a: gpio-controller@1400 { + #gpio-cells = <2>; + compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank"; + reg = <0x1400 0x18>; + gpio-controller; + }; + + qe_pio_e: gpio-controller@1460 { + #gpio-cells = <2>; + compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank"; + reg = <0x1460 0x18>; + gpio-controller; + }; Appendix A - Sample SOC node for MPC8540 ======================================== diff --git a/Documentation/powerpc/phyp-assisted-dump.txt b/Documentation/powerpc/phyp-assisted-dump.txt new file mode 100644 index 00000000000..c4682b982a2 --- /dev/null +++ b/Documentation/powerpc/phyp-assisted-dump.txt @@ -0,0 +1,127 @@ + + Hypervisor-Assisted Dump + ------------------------ + November 2007 + +The goal of hypervisor-assisted dump is to enable the dump of +a crashed system, and to do so from a fully-reset system, and +to minimize the total elapsed time until the system is back +in production use. + +As compared to kdump or other strategies, hypervisor-assisted +dump offers several strong, practical advantages: + +-- Unlike kdump, the system has been reset, and loaded + with a fresh copy of the kernel. In particular, + PCI and I/O devices have been reinitialized and are + in a clean, consistent state. +-- As the dump is performed, the dumped memory becomes + immediately available to the system for normal use. +-- After the dump is completed, no further reboots are + required; the system will be fully usable, and running + in it's normal, production mode on it normal kernel. + +The above can only be accomplished by coordination with, +and assistance from the hypervisor. The procedure is +as follows: + +-- When a system crashes, the hypervisor will save + the low 256MB of RAM to a previously registered + save region. It will also save system state, system + registers, and hardware PTE's. + +-- After the low 256MB area has been saved, the + hypervisor will reset PCI and other hardware state. + It will *not* clear RAM. It will then launch the + bootloader, as normal. + +-- The freshly booted kernel will notice that there + is a new node (ibm,dump-kernel) in the device tree, + indicating that there is crash data available from + a previous boot. It will boot into only 256MB of RAM, + reserving the rest of system memory. + +-- Userspace tools will parse /sys/kernel/release_region + and read /proc/vmcore to obtain the contents of memory, + which holds the previous crashed kernel. The userspace + tools may copy this info to disk, or network, nas, san, + iscsi, etc. as desired. + + For Example: the values in /sys/kernel/release-region + would look something like this (address-range pairs). + CPU:0x177fee000-0x10000: HPTE:0x177ffe020-0x1000: / + DUMP:0x177fff020-0x10000000, 0x10000000-0x16F1D370A + +-- As the userspace tools complete saving a portion of + dump, they echo an offset and size to + /sys/kernel/release_region to release the reserved + memory back to general use. + + An example of this is: + "echo 0x40000000 0x10000000 > /sys/kernel/release_region" + which will release 256MB at the 1GB boundary. + +Please note that the hypervisor-assisted dump feature +is only available on Power6-based systems with recent +firmware versions. + +Implementation details: +---------------------- + +During boot, a check is made to see if firmware supports +this feature on this particular machine. If it does, then +we check to see if a active dump is waiting for us. If yes +then everything but 256 MB of RAM is reserved during early +boot. This area is released once we collect a dump from user +land scripts that are run. If there is dump data, then +the /sys/kernel/release_region file is created, and +the reserved memory is held. + +If there is no waiting dump data, then only the highest +256MB of the ram is reserved as a scratch area. This area +is *not* released: this region will be kept permanently +reserved, so that it can act as a receptacle for a copy +of the low 256MB in the case a crash does occur. See, +however, "open issues" below, as to whether +such a reserved region is really needed. + +Currently the dump will be copied from /proc/vmcore to a +a new file upon user intervention. The starting address +to be read and the range for each data point in provided +in /sys/kernel/release_region. + +The tools to examine the dump will be same as the ones +used for kdump. + +General notes: +-------------- +Security: please note that there are potential security issues +with any sort of dump mechanism. In particular, plaintext +(unencrypted) data, and possibly passwords, may be present in +the dump data. Userspace tools must take adequate precautions to +preserve security. + +Open issues/ToDo: +------------ + o The various code paths that tell the hypervisor that a crash + occurred, vs. it simply being a normal reboot, should be + reviewed, and possibly clarified/fixed. + + o Instead of using /sys/kernel, should there be a /sys/dump + instead? There is a dump_subsys being created by the s390 code, + perhaps the pseries code should use a similar layout as well. + + o Is reserving a 256MB region really required? The goal of + reserving a 256MB scratch area is to make sure that no + important crash data is clobbered when the hypervisor + save low mem to the scratch area. But, if one could assure + that nothing important is located in some 256MB area, then + it would not need to be reserved. Something that can be + improved in subsequent versions. + + o Still working the kdump team to integrate this with kdump, + some work remains but this would not affect the current + patches. + + o Still need to write a shell script, to copy the dump away. + Currently I am parsing it manually. |