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Andrew Morton wrote: > > Doesn't refusing to boot seem to heavy handed for this bug? The buggy > > CPUs have been around for many years (it is practically the entire AMD > > line for the last 4 years or so), and nobody in userspace has > > complained about the 2.4 behaviour so far. (Linux 2.4 behaviour is, > > of course, to ignore the errata). > > That is the case at present. But the 2.6 kernel was hitting this > erracularity daily. We're talking about what to offer userspace now... I think we all agree that the kernel itself shouldn't be allowed to hit it, one way or another. > If some smart cookie decides to add prefetches to some STL implementation > or something, they are likely to start hitting it with the same frequency. Especially now that GCC has intrinsics for prefetches, and GCC's optimiser can generate prefetches automatically (-fprefetch-loop-arrays). But if they assume the kernel hides it, they'll still hit it on any of the huge installed base of <=4 year old AMD boxes running 2.2 and 2.4. Ideally, userspace should just not compile with prefetch if they think they might run on one of those - or select different code at run time - it is not so different from the constraints which say SSE code simply won't run on some CPUs or old kernels anyway. (prefetch is worse on a P5 than a K7 - it'll throw an illegal opcode exception :) I understand you're advocating a policy that says we can't do anything about old systems, but from 2.6 onwards apps can depend on not being hit by that erratum in userspace, is that right? -- Jamie - 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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