Messages in this thread | | | Date | Wed, 24 Sep 2008 14:58:08 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH 0/3] x86: restore old GART alloc_coherent |
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On Wed, Sep 24, 2008 at 08:48:34PM +0900, FUJITA Tomonori wrote: > This pachset is against tip/iommu. > > What this patchset does is restoring old GART alloc_coherent behavior > (before the alloc_coherent rewrite): > > http://lkml.org/lkml/2008/8/12/200 > > Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32 > for a device having dma_masks > 24bit < 32bits. If GART gets an > address that a device can't access to, GART tries to map the address > to a virtual I/O address that the device can access to. > > But Andi pointed out, "The GART is somewhere in the 4GB range so you > cannot use it to map anything < 4GB. Also GART is pretty small." > > http://lkml.org/lkml/2008/9/12/43 > > So it's possible that GART doesn't have virtual I/O address space that > a device can access to. The current behavior might not work for a > device having dma_masks > 24bit < 32bits. This patchset restores old > GART alloc_coherent behavior, which doesn't use GART hardware (if an > user doesn't enable force_iommu option).
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
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