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    SubjectRe: [PATCH] VFIO driver: Non-privileged user level PCI drivers
    On 05/29/2010 02:55 PM, Arnd Bergmann wrote:
    > On Saturday 29 May 2010, Tom Lyon wrote:
    >
    >> +/*
    >> + * Structure for DMA mapping of user buffers
    >> + * vaddr, dmaaddr, and size must all be page aligned
    >> + * buffer may only be larger than 1 page if (a) there is
    >> + * an iommu in the system, or (b) buffer is part of a huge page
    >> + */
    >> +struct vfio_dma_map {
    >> + __u64 vaddr; /* process virtual addr */
    >> + __u64 dmaaddr; /* desired and/or returned dma address */
    >> + __u64 size; /* size in bytes */
    >> + int rdwr; /* bool: 0 for r/o; 1 for r/w */
    >> +};
    >>
    > Please add a 32 bit padding word at the end of this, otherwise the
    > size of the data structure is incompatible between 32 x86 applications
    > and 64 bit kernels.
    >

    Might as well call it 'flags' and reserve a bit more space (keeping
    64-bit aligned size) for future expansion.

    rdwr can be folded into it.

    --
    I have a truly marvellous patch that fixes the bug which this
    signature is too narrow to contain.



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