Re: asm (lidt) question

[Davide Libenzi <davidel@xmailserver.org>]

On Thu, 17 Jul 2003, Randy.Dunlap wrote:

>
> In arch/i386/kernel, inline asm for loading IDT (lidt) is used a few
> times, but with slightly different constraints and output/input
> definitions.  Are these OK, equivalent, or what?
>
> [rddunlap@dragon kernel]$ findc lidt
> ./cpu/common.c:484: __asm__ __volatile__("lidt %0": "=m" (idt_descr));
> ./traps.c:783:	__asm__ __volatile__("lidt %0": "=m" (idt_descr));
>
> vs.
>
> ./reboot.c:186:	__asm__ __volatile__ ("lidt %0" : : "m" (real_mode_idt));
> ./reboot.c:261:	__asm__ __volatile__("lidt %0": :"m" (no_idt));
> ./suspend.c:95:	asm volatile ("lidt %0" :: "m" (saved_context.idt_limit));

I'd have said no looking at the syntax (input/output), but they indeed
generate the same code (just checked).



- Davide