Re: Help in finding the cycle counter for mips and mipsel
On Sat, May 03, 2003 at 10:33:53PM +0200, Guido Guenther wrote:
> On Sat, May 03, 2003 at 10:12:22PM +0200, Thiemo Seufer wrote:
> > Guido Guenther wrote:
> > > You wrote:
> > > > First, if the linux kernel can be believed, the way to access the
> > > > cycle counter can be found in linux/include/asm-mips/timex.h. This is
> > > I think this will cause an "Illegal instruction"
> >
> > "coprocessor unusable", I think.
> Userspace is seeing a SIGILL. That's all I ment to say.
>
> > > when used from user
> > > mode since this uses the bfc0 instruction. I'm not sure if you can
> > > access the cycle counter from user mode at all.
> >
> > It won't help anyway, as the counter is only avalable for R4000
> > style CPUs, and used for the jiffies counter by the kernel.
> Looking at the fftw3 code this looks like the kind of counter James was
> looking for.
You said above that acessing the counter as I described will cause the
program to die. This is in fact what happened on mips and mipsel when I
uploaded the package (see
http://buildd.debian.org/fetch.php?&pkg=fftw3&ver=3.0-3&arch=mipsel&stamp=1052265785&file=log&as=raw).
The question is, how does one access the counter from userspace? It is
possible to compile using --without-cycle-counter. Should I simply do
that for mips and mipsel?
--
James (Jay) Treacy
treacy@debian.org
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