Re: [PATCH] EFI: Only set regions uncacheable if they support it

[Matthew Garrett]

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@xxxxxxxxxx>
> 
> 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@xxxxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/