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2009-06-22 Robert Millan <rmh.grub@aybabtu.com>

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* kern/i386/pc/startup.S (real_to_prot): Move from here ...
        * kern/i386/realmode.S (real_to_prot): ... to here.
This commit is contained in:
robertmh 2009-06-22 10:42:37 +00:00
parent bf3372349c
commit 41da966565
3 changed files with 59 additions and 61 deletions
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5
ChangeLog
View file

@ -1,3 +1,8 @@
2009-06-22 Robert Millan <rmh.grub@aybabtu.com>
* kern/i386/pc/startup.S (real_to_prot): Move from here ...
* kern/i386/realmode.S (real_to_prot): ... to here.
2009-06-22 Robert Millan <rmh.grub@aybabtu.com>
* conf/i386-ieee1275.rmk (pkglib_PROGRAMS): Replace `kernel.elf'

59
kern/i386/pc/startup.S
View file

@ -290,8 +290,6 @@ codestart:
*/
call EXT_C(grub_main)
#include "../realmode.S"
/*
* This is the area for all of the special variables.
*/
@ -301,62 +299,7 @@ VARIABLE(grub_boot_drive)
.p2align 2 /* force 4-byte alignment */
/*
* These next two routines, "real_to_prot" and "prot_to_real" are structured
* in a very specific way. Be very careful when changing them.
*
* NOTE: Use of either one messes up %eax and %ebp.
*/
real_to_prot:
.code16
cli
/* load the GDT register */
#ifdef APPLE_CC
mov %cs, %ax
mov %ax, %ds
DATA32 ADDR32 lgdt gdtdesc
#else
DATA32 ADDR32 lgdt %cs:gdtdesc
#endif
/* turn on protected mode */
movl %cr0, %eax
orl $GRUB_MEMORY_MACHINE_CR0_PE_ON, %eax
movl %eax, %cr0
/* jump to relocation, flush prefetch queue, and reload %cs */
DATA32 ljmp $GRUB_MEMORY_MACHINE_PROT_MODE_CSEG, $protcseg
.code32
protcseg:
/* reload other segment registers */
movw $GRUB_MEMORY_MACHINE_PROT_MODE_DSEG, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
/* put the return address in a known safe location */
movl (%esp), %eax
movl %eax, GRUB_MEMORY_MACHINE_REAL_STACK
/* get protected mode stack */
movl protstack, %eax
movl %eax, %esp
movl %eax, %ebp
/* get return address onto the right stack */
movl GRUB_MEMORY_MACHINE_REAL_STACK, %eax
movl %eax, (%esp)
/* zero %eax */
xorl %eax, %eax
/* return on the old (or initialized) stack! */
ret
#include "../realmode.S"
/*
* grub_gate_a20(int on)

56
kern/i386/realmode.S
View file

@ -110,12 +110,62 @@ gdtdesc:
.long gdt /* addr */
/*
* These next routine, "prot_to_real" is structured in a very
* specific way. Be very careful when changing it.
* These next two routines, "real_to_prot" and "prot_to_real" are structured
* in a very specific way. Be very careful when changing them.
*
* NOTE: Use of it messes up %eax and %ebp.
* NOTE: Use of either one messes up %eax and %ebp.
*/
real_to_prot:
.code16
cli
/* load the GDT register */
#ifdef APPLE_CC
mov %cs, %ax
mov %ax, %ds
DATA32 ADDR32 lgdt gdtdesc
#else
DATA32 ADDR32 lgdt %cs:gdtdesc
#endif
/* turn on protected mode */
movl %cr0, %eax
orl $GRUB_MEMORY_MACHINE_CR0_PE_ON, %eax
movl %eax, %cr0
/* jump to relocation, flush prefetch queue, and reload %cs */
DATA32 ljmp $GRUB_MEMORY_MACHINE_PROT_MODE_CSEG, $protcseg
.code32
protcseg:
/* reload other segment registers */
movw $GRUB_MEMORY_MACHINE_PROT_MODE_DSEG, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
/* put the return address in a known safe location */
movl (%esp), %eax
movl %eax, GRUB_MEMORY_MACHINE_REAL_STACK
/* get protected mode stack */
movl protstack, %eax
movl %eax, %esp
movl %eax, %ebp
/* get return address onto the right stack */
movl GRUB_MEMORY_MACHINE_REAL_STACK, %eax
movl %eax, (%esp)
/* zero %eax */
xorl %eax, %eax
/* return on the old (or initialized) stack! */
ret
prot_to_real:
/* just in case, set GDT */
lgdt gdtdesc