2a43f3ede4
Defining __PHYSICAL_START and __KERNEL_START in asm-i386/page.h works but it triggers a full kernel rebuild for the silliest of reasons. This modifies the users to directly use CONFIG_PHYSICAL_START and linux/config.h which prevents the full rebuild problem, which makes the code much more maintainer and hopefully user friendly. 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>
128 lines
2.8 KiB
ArmAsm
128 lines
2.8 KiB
ArmAsm
/*
|
|
* linux/boot/head.S
|
|
*
|
|
* Copyright (C) 1991, 1992, 1993 Linus Torvalds
|
|
*/
|
|
|
|
/*
|
|
* head.S contains the 32-bit startup code.
|
|
*
|
|
* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
|
|
* the page directory will exist. The startup code will be overwritten by
|
|
* the page directory. [According to comments etc elsewhere on a compressed
|
|
* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
|
|
*
|
|
* Page 0 is deliberately kept safe, since System Management Mode code in
|
|
* laptops may need to access the BIOS data stored there. This is also
|
|
* useful for future device drivers that either access the BIOS via VM86
|
|
* mode.
|
|
*/
|
|
|
|
/*
|
|
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
|
|
*/
|
|
.text
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
|
|
.globl startup_32
|
|
|
|
startup_32:
|
|
cld
|
|
cli
|
|
movl $(__BOOT_DS),%eax
|
|
movl %eax,%ds
|
|
movl %eax,%es
|
|
movl %eax,%fs
|
|
movl %eax,%gs
|
|
|
|
lss stack_start,%esp
|
|
xorl %eax,%eax
|
|
1: incl %eax # check that A20 really IS enabled
|
|
movl %eax,0x000000 # loop forever if it isn't
|
|
cmpl %eax,0x100000
|
|
je 1b
|
|
|
|
/*
|
|
* Initialize eflags. Some BIOS's leave bits like NT set. This would
|
|
* confuse the debugger if this code is traced.
|
|
* XXX - best to initialize before switching to protected mode.
|
|
*/
|
|
pushl $0
|
|
popfl
|
|
/*
|
|
* Clear BSS
|
|
*/
|
|
xorl %eax,%eax
|
|
movl $_edata,%edi
|
|
movl $_end,%ecx
|
|
subl %edi,%ecx
|
|
cld
|
|
rep
|
|
stosb
|
|
/*
|
|
* Do the decompression, and jump to the new kernel..
|
|
*/
|
|
subl $16,%esp # place for structure on the stack
|
|
movl %esp,%eax
|
|
pushl %esi # real mode pointer as second arg
|
|
pushl %eax # address of structure as first arg
|
|
call decompress_kernel
|
|
orl %eax,%eax
|
|
jnz 3f
|
|
popl %esi # discard address
|
|
popl %esi # real mode pointer
|
|
xorl %ebx,%ebx
|
|
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
|
|
|
|
/*
|
|
* We come here, if we were loaded high.
|
|
* We need to move the move-in-place routine down to 0x1000
|
|
* and then start it with the buffer addresses in registers,
|
|
* which we got from the stack.
|
|
*/
|
|
3:
|
|
movl $move_routine_start,%esi
|
|
movl $0x1000,%edi
|
|
movl $move_routine_end,%ecx
|
|
subl %esi,%ecx
|
|
addl $3,%ecx
|
|
shrl $2,%ecx
|
|
cld
|
|
rep
|
|
movsl
|
|
|
|
popl %esi # discard the address
|
|
popl %ebx # real mode pointer
|
|
popl %esi # low_buffer_start
|
|
popl %ecx # lcount
|
|
popl %edx # high_buffer_start
|
|
popl %eax # hcount
|
|
movl $CONFIG_PHYSICAL_START,%edi
|
|
cli # make sure we don't get interrupted
|
|
ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
|
|
|
|
/*
|
|
* Routine (template) for moving the decompressed kernel in place,
|
|
* if we were high loaded. This _must_ PIC-code !
|
|
*/
|
|
move_routine_start:
|
|
movl %ecx,%ebp
|
|
shrl $2,%ecx
|
|
rep
|
|
movsl
|
|
movl %ebp,%ecx
|
|
andl $3,%ecx
|
|
rep
|
|
movsb
|
|
movl %edx,%esi
|
|
movl %eax,%ecx # NOTE: rep movsb won't move if %ecx == 0
|
|
addl $3,%ecx
|
|
shrl $2,%ecx
|
|
rep
|
|
movsl
|
|
movl %ebx,%esi # Restore setup pointer
|
|
xorl %ebx,%ebx
|
|
ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
|
|
move_routine_end:
|