Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 1 Oct 2003 00:55:28 +0100 | From | Jamie Lokier <> | Subject | Re: [PATCH] Mutilated form of Andi Kleen's AMD prefetch errata patch |
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Dave Jones wrote: > Which gets us back to the question of why this is needed at all ? > You said earlier "In case you hadn't fully grokked it, my code doesn't > disable the workaround!" So why do you need this ?
To change the prefetch workaround from a critical requirement to an optimisation knob.
X86_USE_3DNOW is very similar: if it's enabled, the kernel has some extra code to make certain CPUs run faster, but they also run fine without it. X86_OOSTORE is another.
What I'd really like your opinion on is the appropriate userspace behaviour. If we don't care about fixing up userspace, then __ex_table is a much tidier workaround for the prefetch bug. If we do care about fixing up userspace, then do we need a policy decision that says it's not acceptable to run on AMD without userspace fixups from 2.6.0 onwards - it must fixup userspace or refuse to run?
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