Erwin Authried <[email protected]> wrote:

> I have used XIP with armnommu on mtd devices with 2.4, and I want to use XIP
> with 2.6 now. I have seen David Howell's patches from 2008-9-24 that add the
> necessary support in MTD. In arch/arm, it looks like arch_get_unmapped_area()
> is available for arm with mmu only, is it required to implement this for nommu
> as well to be able to use XIP?

arch_get_unmapped_area() find a piece of unmapped _virtual_ memory space that
can then be mapped to a physical area, so it doesn't make sense to have an
overriding arch one for the NOMMU case: virtual memory is more or less
identical with physical memory - and where in virtual memory a mappable object
will be places depends entirely on where in physical memory it is.

For XIP in NOMMU mode, the device or filesystem driver needs to provide the
get_unmapped_area() file op so that the driver can tell mmap() where the
object exists physically.  This is really an abuse of the API, but it seems to
work.

David
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