Messages in this thread | | | Date | Thu, 15 Mar 2012 07:36:46 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] EFI: Only set regions uncacheable if they support it |
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On 03/15/2012 07:33 AM, Matthew Garrett wrote: >> >> If we map it WB software can do speculative loads from that region which >> would bring it into the cache. If we map it UC we might have to CLFLUSH... > > We've already mapped it at this point - we then go back and flag it UC > if it's not writeback. The latter seems to be causing problems, I'm not > sure we've seen any indication that the former is. And these regions are > marked as runtime accessible, so per spec they do need to be mapped into > address space... >
In other words, it's totally f*cked. I guess at that point mapping it WB and letting the BIOS-configured MTRRs deal with the caching attributes is probably the right thing to do.
I would still really like to understand why we're seeing #MCs... that's bothersome all by itself.
-hpa
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