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Date: Thu, 15 Mar 2012 07:28:30 -0700 From: "H. Peter Anvin" <hpa@...or.com> To: Matthew Garrett <mjg59@...f.ucam.org> CC: linux-kernel@...r.kernel.org, x86@...nel.org, matt.fleming@...el.com Subject: Re: [PATCH] EFI: Only set regions uncacheable if they support it On 03/15/2012 07:24 AM, Matthew Garrett wrote: > On Thu, Mar 15, 2012 at 07:17:56AM -0700, H. Peter Anvin wrote: >> On 03/15/2012 07:07 AM, Matthew Garrett wrote: >>> >>> I have a report of a system that fails to boot with an MCE during EFI >>> setup. The memory range is marked reserved and claims not to support any >>> caching type, which I think probably translates as "Don't do anything to >>> this region ever". >>> >> >> In other words, "don't map me"... not something we really support at the >> moment, but perhaps we should; at least until we find systems in the >> field that break with that constraint :( > > Mapping should be harmless as long as we then don't touch it? I can't > think of any circumstances where we would. > 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... -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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