>>>>> On Fri, 24 Oct 2003 15:16:59 -0700, "Luck, Tony" <tony.luck@intel.com> said: Tony> This patch was accepted into 2.5.55, attributed to "davej@uk". Tony> This code will prefetch from beyond the end of the page table Tony> being cleared ... which is clearly a bad thing if the page Tony> table in question is allocated from the last page of memory Tony> (or precedes a hole on a discontig mem system). >> Different arches behave differently, though. In the case of ia64, >> it'a always safe to prefetch (even with lfetch.fault). Tony> Not quite always ... this was how I found the efi trim.bottom Tony> bug, since Linux had allocated a pgd at 0xa00000-16k, and the Tony> lfetch that reached out beyond the end of the page to the Tony> uncacheable address 0xa00000 took an MCA. But don't confuse cause and effect! The MCA was caused by a bad TLB entry. The lfetch only triggered the latent bug (as might have a instruction-prefetch). Tony> A pgd in the last page of a granule that is followed by an uncacheable Tony> address would do the same with lfetch.fault, wouldn't it? No, lfetch to uncacheable translations have no effect. --david - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.htmlReceived on Fri Oct 24 19:10:45 2003
This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:19 EST