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qemu: Fix compilation

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This commit is contained in:
Vladimir Serbinenko 2015-02-21 19:55:53 +01:00
parent 44ff462e83
commit e62ca2a870
2 changed files with 20 additions and 2 deletions
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2
grub-core/boot/i386/qemu/boot.S
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@ -48,7 +48,7 @@ VARIABLE(grub_core_entry_addr)
/* Transition to protected mode. We use pushl to force generation
of a flat return address. */
pushl $1f
jmpl real_to_prot
jmp real_to_prot
.code32
/* Ensure A20 is enabled. We're in qemu, so control port A works
and there is no need to wait since there is no real logic, it's

20
grub-core/kern/i386/realmode.S
View file

@ -137,7 +137,22 @@ real_to_prot:
/* load the GDT register */
xorw %ax, %ax
movw %ax, %ds
#ifdef GRUB_MACHINE_QEMU
/*
qemu is special: gdtdesc is in ROM.
%cs = 0xf000
_start + GRUB_BOOT_MACHINE_SIZE = 0x100000
So
_start + GRUB_BOOT_MACHINE_SIZE - 0x10000 points to the same point
as %cs.
gdtdesc - (_start + GRUB_BOOT_MACHINE_SIZE - 0x10000)
= gdtdesc - _start - GRUB_BOOT_MACHINE_SIZE + 0x10000
but the later can be computed by assembly.
*/
lgdtl %cs:(gdtdesc - _start - GRUB_BOOT_MACHINE_SIZE + 0x10000)
#else
lgdtl gdtdesc
#endif
/* turn on protected mode */
movl %cr0, %eax
@ -178,6 +193,9 @@ protcseg:
/* return on the old (or initialized) stack! */
ret
/* prot_to_real assumes that this code is under 64K which is not
true for qemu. */
#ifndef GRUB_MACHINE_QEMU
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 1999,2000,2001,2002,2003,2005,2006,2007,2009,2010 Free Software Foundation, Inc.
@ -259,5 +277,5 @@ realcseg:
/* return on new stack! */
retl
#endif
.code32