On Monday 15 October 2007 21:07, Andi Kleen wrote: > On Tue, Oct 16, 2007 at 12:56:46AM +1000, Nick Piggin wrote: > > Is this true even if you don't write through those old mappings? > > I think it happened for reads too. It is a little counter intuitive > because in theory the CPU doesn't need to write back non dirty lines, > but in the one case which took so long to debug exactly this happened > somehow. > > At it is undefined for reads and writes in the architecture so > better be safe than sorry.
Yes, typo. I meant reads or writes. > And x86 CPUs are out of order and do speculative executation > and that can lead to arbitary memory accesses even if the code > never touches an particular address. > > Newer Intel CPUs have something called self-snoop which was supposed > to handle this; but in some situations it doesn't seem to catch it > either. Fair enough, so we have to have this lazy tlb flush hook for Xen/PAT/etc. I don't think it should be much problem to implement. > > Is DRM or AGP then not also broken with lazy highmem flushing, or > > how do they solve that? > > AGP doesn't allocate highmem pages. Not sure about the DRM code. Hmm, OK. It looks like DRM vmallocs memory (which gives highmem). - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
