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/* startup.S - bootstrap GRUB itself */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2018 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <grub/symbol.h>
#include <grub/machine/memory.h>
.file "startup_pvh.S"
.text
.globl start, _start
.code32
start:
_start:
cld
lgdt gdtdesc
ljmp $GRUB_MEMORY_MACHINE_PROT_MODE_CSEG, $1f
1:
movl $GRUB_MEMORY_MACHINE_PROT_MODE_DSEG, %eax
mov %eax, %ds
mov %eax, %es
mov %eax, %fs
mov %eax, %gs
mov %eax, %ss
leal LOCAL(stack_end), %esp
/* Save address of start info structure. */
mov %ebx, pvh_start_info
call EXT_C(grub_main)
/* Doesn't return. */
.p2align 3
gdt:
.word 0, 0
.byte 0, 0, 0, 0
/* -- code segment --
* base = 0x00000000, limit = 0xFFFFF (4 KiB Granularity), present
* type = 32bit code execute/read, DPL = 0
*/
.word 0xFFFF, 0
.byte 0, 0x9A, 0xCF, 0
/* -- data segment --
* base = 0x00000000, limit 0xFFFFF (4 KiB Granularity), present
* type = 32 bit data read/write, DPL = 0
*/
.word 0xFFFF, 0
.byte 0, 0x92, 0xCF, 0
.p2align 3
/* this is the GDT descriptor */
gdtdesc:
.word 0x17 /* limit */
.long gdt /* addr */
.p2align 2
/* Saved pointer to start info structure. */
.globl pvh_start_info
pvh_start_info:
.long 0
.bss
.space GRUB_MEMORY_MACHINE_PROT_STACK_SIZE
LOCAL(stack_end):
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