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Date: Thu, 15 Mar 2012 14:07:08 +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 07:00:06AM -0700, H. Peter Anvin wrote: > On 03/15/2012 06:56 AM, Matthew Garrett wrote: > > The EFI memory region attributes field indicates whether the region can > > be mapped with various cache attributes. Our current implementation always > > marks regions uncacheable if they don't have the writeback support flag. > > This causes us to mark some regions uncacheable even if they don't > > indicate support for being uncacheable, triggering a clflush that may cause > > an MCE. Ensure we only do this for regions which support it. > > > > Signed-off-by: Matthew Garrett <mjg@...hat.com> > > Could you be specific as to what you're seeing in the field? In > particular, what *do* these memory regions claim to support? 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". -- 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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