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#
# minimal bootstrap to set up flat 32-bit protected mode
#
bstart = 0xf0000
.code16
start:
cs lidtl idt_desc
cs lgdtl gdt_desc
mov %cr0, %eax
or $1, %eax
mov %eax, %cr0
ljmpl $8, $pmode + bstart
pmode:
.code32
mov $0x10, %ax
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss
mov $0xa0000, %esp
ljmp $8, $0x100000
.align 16
idt_desc:
.word 0
.long 0
gdt_desc:
.word gdt_end - gdt - 1
.long gdt + bstart
.align 16
gdt:
.quad 0
.quad 0x00cf9b000000ffff # flat 32-bit code segment
.quad 0x00cf93000000ffff # flat 32-bit data segment
gdt_end:
. = 0xfff0
.code16
ljmp $0xf000, $start
.align 65536
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