Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata

Dave Jones
2003-09-18T14:06:25Z

On Thu, Sep 18, 2003 at 09:43:31AM +0200, Pavel Machek wrote:

> > The user space problem worries me more, because the expectation
> > is that if CPUID says the program can use perfetch, it could
> > and should regardless of what the kernel decided to do here.
>
> User programs should not rely on cpuid;

Depends. /dev/cpu/x/cpuid is preferred over cpuinfo, as it remains
constant across kernel versions.

> they should read /proc/cpuinfo exactly because this kind of errata.

We don't do any change to /proc/cpuinfo in this case. As I mentioned
in an earlier mail, the only way you could disable prefetch in this way
would be by reporting the entire sse/3dnow instruction sets as unavailable
which is overkill.

With Andi's fix, userspace programs doing prefetch get fixed up
transparently, making this a non-issue.

Dave

--
Dave Jones http://www.codemonkey.org.uk