Messages in this thread | | | Subject | Re: [PATCH] drm: i915: ensure objects are allocated below 4GB on PAE | From | Eric Anholt <> | Date | Wed, 27 May 2009 10:40:12 -0700 |
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On Wed, 2009-05-27 at 08:42 +0800, Shaohua Li wrote: > On Wed, May 27, 2009 at 08:18:40AM +0800, Kyle McMartin wrote: > > On Tue, May 26, 2009 at 11:55:50PM +0100, Hugh Dickins wrote: > > > I'm confused: I thought GFP_DMA32 only applies on x86_64: > > > my 32-bit PAE machine with (slightly!) > 4GB shows no ZONE_DMA32. > > > Does this patch perhaps depend on another, to enable DMA32 on 32-bit > > > PAE, or am I just in a muddle? > > > > > > > No, you're exactly right, I'm just a muppet and missed the obvious. > > Looks like the "correct" fix is the fact that the allocation is thus > > filled out with GFP_USER, therefore, from ZONE_NORMAL, and below > > max_low_pfn. > > > > Looks like we'll need some additional thinking to get true ZONE_DMA32 on > > i386... ugh, I'll look into it tonight. > For i386, GFP_USER is enough. But 945G GART can only map to physical page < 4G, > so for x64, we need GFP_DMA32. This is the reason I add extra GFP_DMA32.
Those 945Gs don't have memory located above 4G, from my reading of the chipset specs.
-- Eric Anholt eric@anholt.net eric.anholt@intel.com
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