使用AT&T汇编语法改写linux0.00的boot.s

BOOTSEG = 0x07c0
SYSSEG = 0x1000
SYSLEN = 17

.code16
.align 2
.text
.globl _start
_start:
    ljmp $BOOTSEG, $go
go:
    movw %cs, %ax
    movw %ax, %ds
    movw %ax, %ss
    movw %ax, %es
    movw $0x0400, %sp
load_system:
    movw $0x0000, %dx
    movw $0x0002, %cx
    movw $SYSSEG, %ax
    movw %ax, %es
    xorw %bx, %bx
    movw $0x200+SYSLEN, %ax
    int $0x13
    jnc ok_load
die:
    ljmp $BOOTSEG, $die
ok_load:
    cli
    movw $SYSSEG, %ax
    movw %ax, %ds
    xorw %si, %si
    xorw %ax, %ax
    movw %ax, %es
    xorw %di, %di
    movw $0x1000, %cx
    cld
    rep movsw
    
    movw $BOOTSEG, %ax
    movw %ax, %ds
    lidt idt_48
    lgdt gdt_48
    
    movw $0x0001, %ax
    lmsw %ax
    ljmp $8, $0

gdt:
    .word 0, 0, 0, 0

    .word 0x07FF
    .word 0x0000
    .word 0x9A00
    .word 0x00c0    

    .word 0x07ff
    .word 0x0000
    .word 0x9200
    .word 0x00c0

idt_48:
    .word 0
    .word 0, 0
gdt_48:
    .word 0x7ff
    .word 0x7c00+gdt, 0
.org 510
    .word 0xaa55

 

/*
AS =as
LD =ld
LDFLAGS =-m elf_i386 -Ttext 0 -e startup_32 -s -x -M  

all: Image

Image: boot system
    objcopy -O binary boot.o Image
    objcopy -O binary system head
    cat head >> Image

head.o: head.s

system: head.o 
    $(LD) $(LDFLAGS) head.o  -o system > System.map

boot: boot.s
    $(AS) -o boot.o boot.s

clean:
    rm -f Image System.map core boot *.o system
*/