Messages in this thread | | | From | (bill davidsen) | Subject | Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata | Date | 11 Sep 2003 19:56:41 GMT |
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In article <3F6087FC.7090508@pobox.com>, Jeff Garzik <jgarzik@pobox.com> wrote: | Andi Kleen wrote: | > It was not created for that (I know that because I created it ;-) | | hehe | | | > X86_GENERIC is merely an optimization hint (currently it only changes the cache | > line size hint) It does not change anything related to correctness. Everything | > that handles correctness is checked unconditionally. | | When, building non-Pentium4-related code when CONFIG_MPENTIUM4 && | !CONFIG_X86_GENERIC, it's OK that the code is incorrect for (picking | example) AMD processors. | | It would be a user bug to boot that on an AMD box, just like it would be | user bug to boot a CONFIG_M586 kernel on an ancient 386. | | | > is_prefetch is a correctness thing. | | When we know at compile time it's not needed, it should not be enabled.
Clearly that's right. This buys nothing on CPUs which don't have the problem, why have *any* overhead in size and speed? It's too bad that people have to read around all that code, they don't need to give it a home in their RAM and execute it as well. -- bill davidsen <davidsen@tmr.com> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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