diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2006-12-07 02:14:04 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:04 +0100 |
| commit | 968de4f02621db35b8ae5239c8cfc6664fb872d8 (patch) | |
| tree | 9388da7f18f9511e1bbfeaf934cba8dbc696e9f4 /arch/i386/boot/setup.S | |
| parent | fd593d12770d4a0d1ff095d44b96436c18479ee8 (diff) | |
[PATCH] i386: Relocatable kernel support
This patch modifies the i386 kernel so that if CONFIG_RELOCATABLE is
selected it will be able to be loaded at any 4K aligned address below
1G. The technique used is to compile the decompressor with -fPIC and
modify it so the decompressor is fully relocatable. For the main
kernel relocations are generated. Resulting in a kernel that is relocatable
with no runtime overhead and no need to modify the source code.
A reserved 32bit word in the parameters has been assigned
to serve as a stack so we figure out where are running.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/i386/boot/setup.S')
| -rw-r--r-- | arch/i386/boot/setup.S | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/arch/i386/boot/setup.S b/arch/i386/boot/setup.S index 3aec4538a11..9aa8b051818 100644 --- a/arch/i386/boot/setup.S +++ b/arch/i386/boot/setup.S @@ -588,11 +588,6 @@ rmodeswtch_normal: call default_switch rmodeswtch_end: -# we get the code32 start address and modify the below 'jmpi' -# (loader may have changed it) - movl %cs:code32_start, %eax - movl %eax, %cs:code32 - # Now we move the system to its rightful place ... but we check if we have a # big-kernel. In that case we *must* not move it ... testb $LOADED_HIGH, %cs:loadflags @@ -788,11 +783,12 @@ a20_err_msg: a20_done: #endif /* CONFIG_X86_VOYAGER */ -# set up gdt and idt +# set up gdt and idt and 32bit start address lidt idt_48 # load idt with 0,0 xorl %eax, %eax # Compute gdt_base movw %ds, %ax # (Convert %ds:gdt to a linear ptr) shll $4, %eax + addl %eax, code32 addl $gdt, %eax movl %eax, (gdt_48+2) lgdt gdt_48 # load gdt with whatever is @@ -851,9 +847,26 @@ flush_instr: # Manual, Mixing 16-bit and 32-bit code, page 16-6) .byte 0x66, 0xea # prefix + jmpi-opcode -code32: .long 0x1000 # will be set to 0x100000 - # for big kernels +code32: .long startup_32 # will be set to %cs+startup_32 .word __BOOT_CS +.code32 +startup_32: + movl $(__BOOT_DS), %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + movl %eax, %ss + + xorl %eax, %eax +1: incl %eax # check that A20 really IS enabled + movl %eax, 0x00000000 # loop forever if it isn't + cmpl %eax, 0x00100000 + je 1b + + # Jump to the 32bit entry point + jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi) +.code16 # Here's a bunch of information about your current kernel.. kernel_version: .ascii UTS_RELEASE |