Hi, every body ,I am looking in setup.S
code.
Whn setup GDT ,GDTR save the base address of GDT .
gdt:
.word 0,0,0,0 ! dummy
!!!gdt+8 ( added by me)
.word 0,0,0,0 ! unused
.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
.word 0x0000 ! base address=0
.word 0x9A00 ! code read/exec
.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
!!kernel code segmentation
.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
.word 0x0000 ! base address=0
.word 0x9200 ! data read/write
.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
!!!gdt+32 ( added by me)
idt_48:
.word 0 ! idt limit=0
.word 0,0 ! idt base=0L
!!!gdt+38 ( added by me)
gdt_48:
.word 0x800 ! gdt limit=2048, 256 GDT entries 最多256个GDT表项
.word 512+gdt,0x9 ! gdt base = 0X9xxxx
.............
Why is 512 ????
>From the lable of gdt to gdt_48 ,there are not 512 bytes distance .
Can anyone tell me the reason ???
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