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    SubjectRe: [PATCH 06/14] Pramfs: Include files
    Arnd Bergmann wrote:
    > On Wednesday 24 June 2009, Marco Stornelli wrote:
    >>> Actually, reading from /dev/mem is only valid on real RAM. If the nvram
    >>> is part of an IO memory mapping, you have to do mmap()+memcpy() rather
    >>> than read(). So dd won't do it, but it's still easy to read from user
    >>> space.
    >> For "security" reasons pram reserve the region of memory with
    >> reserve_mem_region_exclusive().....
    >
    > That will only prevent other device drivers from stepping on it,
    > /dev/mem does not care about mem_region reservations.
    >
    > Arnd <><
    >

    Userland may not map this resource, so /dev/mem and the sysfs MMIO
    access will not be allowed. This restriction depends on STRICT_DEVMEM
    option. It's true that currently is only implemented in the x86 world.

    Marco



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