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    SubjectRe: DMA using data buffer vmapped in kernel space
    Date
    Am Donnerstag, 4. März 2010 22:36:34 schrieb Russell King - ARM Linux:
    > Cache maintainence is done using virtual addresses for L1, and
    > physical addresses for L2. There's the need for virtual addresses
    > to be translatable to physical addresses, which is only true for
    > the kernel direct mapped region (pages between PAGE_OFFSET and
    > high_memory).

    Isn't the mapping created by vmap() sufficient for the virt/phys
    translation? In which way is this case different from a buffer
    passed in from user space, where the constituent pages are not
    in the directly mapped kernel region either?

    tk

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