Messages in this thread | | | Date | Wed, 14 Nov 2012 13:55:34 -0800 | From | Jesse Barnes <> | Subject | Re: [PATCH] x86/Sandy Bridge: reserve pages when integrated graphics is present |
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On Wed, 14 Nov 2012 21:19:05 +0000 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Wed, 14 Nov 2012 20:43:31 +0000 > Jesse Barnes <jbarnes@virtuousgeek.org> wrote: > > > SNB graphics devices have a bug that prevent them from accessing certain > > memory ranges, namely anything below 1M and in the pages listed in the > > table. So reserve those at boot if set detect a SNB gfx device on the > > CPU to avoid GPU hangs. > > What happens if the other addresses map to an external memory object - eg > a PCI device which is a legitimate DMA source for video overlay etc ?
Other addresses as in the 5 pages high in the address space? I'm not sure how to do what I want with memblock, doesn't it just allocate RAM not I/O space?... /me looks at the memblock API
Or do you mean if we map GTT pages to point at some non-RAM region will SNB gfx be able to decode them? If that's the question, then I think the answer is no, but I don't have enough detail on the hw bug to be certain.
> I assume this is just for GPU fetches from main memory ?
AIUI, it's an address decoder bug, so it would affect any fetch by the GPU through its memory interface glue.
-- Jesse Barnes, Intel Open Source Technology Center
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