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    SubjectRe: [PATCH] x86: fix nommu_alloc_coherent allocation with NULL device argument
    Andi,

    I guess you made the dma_mask of the fallback_dev 32 bit a long time
    ago. Is there any reason it cannot be 24 bit?

    Joerg

    On Fri, Sep 05, 2008 at 12:40:49PM +0200, Joerg Roedel wrote:
    > I agree with this patch in principle. It fixes the problem. But I think
    > we should evaluate if we can change the dma_mask of the fallback_dev to
    > 24 bit.
    >
    > On Fri, Sep 05, 2008 at 05:58:47PM +0900, FUJITA Tomonori wrote:
    > > We need to use __GFP_DMA for NULL device argument (fallback_dev) with
    > > pci-nommu. It's a hack for ISA (and some old code) so we need to use
    > > GFP_DMA.
    > >
    > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
    > > ---
    > > arch/x86/kernel/pci-nommu.c | 5 +----
    > > include/asm-x86/dma-mapping.h | 2 ++
    > > 2 files changed, 3 insertions(+), 4 deletions(-)
    > >
    > > diff --git a/arch/x86/kernel/pci-nommu.c b/arch/x86/kernel/pci-nommu.c
    > > index 73853d3..526b2db 100644
    > > --- a/arch/x86/kernel/pci-nommu.c
    > > +++ b/arch/x86/kernel/pci-nommu.c
    > > @@ -83,7 +83,6 @@ nommu_alloc_coherent(struct device *hwdev, size_t size,
    > > if (hwdev->dma_mask == NULL)
    > > return NULL;
    > >
    > > - gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
    > > gfp |= __GFP_ZERO;
    > >
    > > dma_mask = hwdev->coherent_dma_mask;
    > > @@ -96,14 +95,12 @@ nommu_alloc_coherent(struct device *hwdev, size_t size,
    > > node = dev_to_node(hwdev);
    > >
    > > #ifdef CONFIG_X86_64
    > > - if (dma_mask <= DMA_32BIT_MASK)
    > > + if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA))
    > > gfp |= GFP_DMA32;
    > > #endif
    > > -
    > > /* No alloc-free penalty for ISA devices */
    > > if (dma_mask == DMA_24BIT_MASK)
    > > gfp |= GFP_DMA;
    > > -
    >
    > Please leave these spare lines where they are. They increase the
    > readability of the code imho.
    >
    > > again:
    > > page = alloc_pages_node(node, gfp, get_order(size));
    > > if (!page)
    > > diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h
    > > index 3a9a6f5..de4495e 100644
    > > --- a/include/asm-x86/dma-mapping.h
    > > +++ b/include/asm-x86/dma-mapping.h
    > > @@ -246,6 +246,8 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
    > > struct dma_mapping_ops *ops = get_dma_ops(dev);
    > > void *memory;
    > >
    > > + gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
    > > +
    > > if (dma_alloc_from_coherent(dev, size, dma_handle, &memory))
    > > return memory;
    > >
    > > --
    > > 1.5.4.2
    > >
    > >
    >
    > --
    > | AMD Saxony Limited Liability Company & Co. KG
    > Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany
    > System | Register Court Dresden: HRA 4896
    > Research | General Partner authorized to represent:
    > Center | AMD Saxony LLC (Wilmington, Delaware, US)
    > | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy
    >
    > _______________________________________________
    > iommu mailing list
    > iommu@lists.linux-foundation.org
    > https://lists.linux-foundation.org/mailman/listinfo/iommu
    >

    --
    | AMD Saxony Limited Liability Company & Co. KG
    Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany
    System | Register Court Dresden: HRA 4896
    Research | General Partner authorized to represent:
    Center | AMD Saxony LLC (Wilmington, Delaware, US)
    | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy



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