Messages in this thread | | | Subject | Re: [PATCH 03/17] pci: Only allow WC mmap on prefetchable resources | From | David Woodhouse <> | Date | Fri, 24 Mar 2017 17:04:34 +0000 |
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On Fri, 2017-03-24 at 17:05 +0100, Arnd Bergmann wrote: > On Wed, Mar 22, 2017 at 2:25 PM, David Woodhouse <dwmw2@infradead.org> wrote: > > > > From: David Woodhouse <dwmw@amazon.co.uk> > > > > The /proc/bus/pci mmap interface allows the user to specify whether they > > want WC or not. Don't let them do so on non-prefetchable BARs. > > > > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> > > Cc: stable@vger.kernel.org > Can you explain this a little more? I understand that we usually want to use > WC mappings on prefetchable BARs, and uncached non-WC on > non-prefetchable, but why do we have to force an error here? > > Couldn't there be some hardware that allows write-combining access > but no prefetches?
Note that this is only for the procfs interface. The sysfs interface already imposes the same restriction by just *not* creating the 'resourceX_wc' attr when the resource isn't prefetchable. So this just brings procfs into line.[unhandled content-type:application/x-pkcs7-signature] | |