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

[Jamie Lokier]

richard.brunner@xxxxxxx wrote:
> Andi's patch solves both the kernel space and the user space
> issues in a pretty small footprint.

Not really.  Userspace still has a problem when run on older kernels,
so it will have to check for AMD and kernel version anyway before
deciding to use the prefetch instruction.  That, or install SIGSEGV
and SIGBUS handlers to do the fixup in userspace.

> 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.

If the workaround isn't compiled in, "prefetch" should be removed from
/proc/cpuinfo on the buggy chips.

-- Jamie
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/