Re: A few Decstation questions.

[Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>]

Len Sorensen wrote:
> On Wed, Apr 09, 2003 at 12:40:28AM +0200, Guido Guenther wrote:
> > Please try:
> >  http://honk.physik.uni-konstanz.de/linux-mips/kernels/kernel-image-2.4.19-r3k-kn02_2.4.19-0.020911.7_mipsel.deb 
> 
> Is there any way to write a small assembly program that tests for ll/sc
> support, rahter than trying to instlal libc6 2.3.1 and smashing the
> system to bits? :)

Something like this (untested) will check for basic operation.

.ent main
.globl main
main:
        addiu   $29, -16
        li      $8, 42
        .set noreorder
        sw      $8, 0($29)
        nop
        .set mips2
        ll      $2, 0($29)
        nop
        sc      $2, 0($29)
        nop
        .set mips0
        .set reorder
        addiu   $29, 16
        jr      $31
.end main

Without ll/sc support, this should crash with SIGILL. Otherwise, it
returns 1 if the ll/sc sequence was atomic and 0 if it wasn't. The
latter should almost never happen.


Thiemo