Not on really old processors. This won't be relevant for the OP anyway because the OP loaded the stack pointer two instructions before the stack segment.gerryg400 wrote:It's not necessary to disable interrupts if the SS is loaded first. The processor does it for you automatically.You should clear interrupt before changing the stack pointer and segment then restore them afterwards.
The [url=http://pdos.csail.mit.edu/6.828/2010/readings/i386.pdf]Intel 80386 Programmer's Reference Manual[/url] wrote:To prevent this situation, the 80386, after both a MOV to SS and a POP to SS instruction, inhibits NMI, INTR, debug exceptions, and single-step traps at the instruction boundary following the instruction that changes SS. Some exceptions may still occur; namely, page fault and general protection fault. Always use the 80386 LSS instruction, and the problem will not occur.
Code: Select all
; Uninterruptible Busy Loop Program (loop.asm)
; Written by Antti
; Compile: nasm -f bin -o loop.img loop.asm
[BITS 16]
start:
cli
xor ax, ax
mov ss, ax
mov sp, ax
mov ax, 0x1000
mov es, ax
cld
mov ax, 0xD08E ; Opcodes: "mov ss, ax"
mov cx, 0x8000
xor di, di
rep stosw ; Fill 0x10000-0x1FFFF with "mov ss, ax"
xor ax, ax
jmp 0x1000:0x0000
times 510 - ($ - $$) db 0
dw 0xAA55
times 1474560 - ($ - $$) db 0 ; "Standard floppy size"