Runtime Altivec detection

Benjamin Herrenschmidt benh at
Sat Mar 8 04:41:05 EST 2003

On Fri, 2003-03-07 at 18:24, Dan Malek wrote:
> Nathan Ingersoll wrote:
> > I've recently been working on some Altivec optimizations for a library,
> > and was looking for a relatively clean way to perform runtime detection.
> For some time now the Linux kernel has provided support for emulating
> the 'mfspr rd, PVR' instruction in user space.  Do this once, get the
> PVR and determine the processor type.
> You can also just read /proc/cpuinfo and search for the 'cpu :' line.
> It will indicate the processor type and if altivec is supported.
> There are probably other ways as well....

There's a much better way. The kernel passes down CPU features
bits down to userland via ELF AUX tables.


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