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    Subjectmmap on a device returns ENODEV

    I couldn't find a specific maintainer to send this to, so the mail list
    will have to do (mmap.c was written by "obz" .. whomever that is)

    I have discovered in the usual way (looking at the code) that it seems
    the 2.2 kernel doesn't support mmap on devices. In the do_mmap function
    (mm/mmap.c:247), ENODEV is returned if the file doesn't support the mmap
    operation. This seems to be the case for block devices. It would be very
    useful if block devices would support mmap because it allows disk
    geometry to be factored into applications requiring high speed disk
    operations. I know that this capability exists on at least Solaris and
    IRIX. So, before attempting to fix this myself, I thought I'd ask the
    following questions:

    A) Has this been implemented anytime after my kernel release 2.2.5-15?
    B) Has anyone even thought about implementing this?
    C) Is there a technical reason why block devices can't be mmap'd?
    D) Would someone far more knowledgeable than me like to step up to
    implementing it?
    E) Would someone far more knowledgeable than me provide some tips on how
    it might be implemented?

    Thanks in advance for your help.

    Reid Spencer
    Chief Technologist, PSW Technologies, Inc.

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