LDT load causing GPF
Posted: Tue Jul 03, 2007 3:54 pm
Whenever I try to switch tasks, I get a GPF with error code 0x18. I set up my LDT in the GDT with type 2, granularity bit 0, base as the start address of my LDT, and limit as size of the ldt - 1.
current_esp and current_ldt are definitely getting set correctly.
Also, when I tried 0x03 instead of 0x18 for the LDT selector, it loaded the LDT without a crash, but then GPFed again when I tried to set CS to 0x04. I used the same flags for the LDT's code segment as I did for the GDT's one at 0x08.
Code: Select all
extern old_esp
global _irq0
_irq0:
pusha
pushf
mov eax, [old_esp]
mov [eax], esp
jmp isr32Code: Select all
; The old esp is saved by the interrupt handler.
extern current_esp, current_ldt
global do_task_switch
do_task_switch:
mov esp, [current_esp]
popf
popa
lldt [current_ldt]
iretAlso, when I tried 0x03 instead of 0x18 for the LDT selector, it loaded the LDT without a crash, but then GPFed again when I tried to set CS to 0x04. I used the same flags for the LDT's code segment as I did for the GDT's one at 0x08.