lkml.org 
[lkml]   [2009]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: How to move two valuables to x86 CPU register ebx, ecx by using AT&A inline asm.
From
On Sun, Nov 22, 2009 at 10:14 PM, Johnny Hung <johnny.hacking@gmail.com> wrote:
> After testing:
>
> # gcc inlineasm.c
> inlineasm.c: Assembler messages:
> inlineasm.c:7: Error: suffix or operands invalid for `out'
> [root@debian-johnny] ~/workspace/test
>
> # cat inlineasm.c
> #include <stdio.h>
>
> int main ()
> {
>    unsigned int val = 5, tmp = 10;
>    asm volatile ("outb $0x27, %%al"
>     :
>     : "a" (0xb2), "b"(val), "c" (tmp)
>    );
> }
>
>    It seems the source of outb instruction cannot be a constant. Is
> there a AT&T instructions document for x86?

In AT&T syntax, the source register comes first. So it should be
"outb %%al, $0x27", assuming that 0x27 is the port number you are
trying to write to.

--
Brian Gerst
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2009-11-23 06:47    [W:0.044 / U:0.416 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site