monitor instruction bug?

H. J. Lu hjl@lucon.org
Mon Oct 10 19:38:00 GMT 2005


On Mon, Oct 10, 2005 at 03:13:12PM -0400, root wrote:
> 
>       mwait              ; 0F 01 C9
> 
> generates:
> 
>       0f                 sidt (bad)
>       01 c9              add ecx,ecx
> 
> 
> (ref: p3-556 IA-32 Intel Architecture Software Developer's Manual
>  Vol 2A: Instruction Set Reference, A-M Order Number 253666)
> 

You can't take a byte out of context for ia32 instruction. I have no
problem:

[hjl@gnu-d tmp]$ cat 1.s
        pause
        monitor
        mwait
[hjl@gnu-d tmp]$ gcc -c 1.s -m32
[hjl@gnu-d tmp]$ objdump -d 1.o

1.o:     file format elf32-i386

Disassembly of section .text:

00000000 <.text>:
   0:   f3 90                   pause
   2:   0f 01 c8                monitor %eax,%ecx,%edx
   5:   0f 01 c9                mwait  %eax,%ecx


H.J.



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