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    SubjectRe: [BK-2.5] Update the generic DMA API to take GFP_ flags on
    On Tue, Jan 14, 2003 at 07:30:23AM -0800, David S. Miller wrote:
    > From: James Bottomley <James.Bottomley@steeleye.com>
    > Date: Tue, 14 Jan 2003 10:30:15 -0500
    >
    > A GFP_KERNEL request is safely implemented as GFP_ATOMIC as long as the caller
    > checks return for NULL. for dma_alloc_coherent return checking is a
    > requirement because the system may return NULL anyway if it is out of mappings
    > even with a GFP_KERNEL flag.
    >
    > Now what about the corollary, a platform that needs
    > to sleep to setup the cpu mapings in a race-free manner?
    >
    > It could not ever honor GFP_ATOMIC in that case.

    That got solved in recent 2.5, albiet with limit of 2MB of consistent /
    coherent allocations at any one time. We return NULL if we run out of
    space, and _all_ callers must check the return code of
    pci_alloc_consistent and/or dma_alloc_coherent no matter what flags they
    pass in.

    --
    Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
    http://www.arm.linux.org.uk/personal/aboutme.html

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