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Open Source and information security mailing list archives
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Date: Thu, 15 Mar 2012 14:33:08 +0000 From: Matthew Garrett <mjg59@...f.ucam.org> To: "H. Peter Anvin" <hpa@...or.com> 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 Thu, Mar 15, 2012 at 07:28:30AM -0700, H. Peter Anvin wrote: > On 03/15/2012 07:24 AM, Matthew Garrett wrote: > > On Thu, Mar 15, 2012 at 07:17:56AM -0700, H. Peter Anvin wrote: > >> 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... 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... -- Matthew Garrett | mjg59@...f.ucam.org -- 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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