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    Subject/dev/mem implementation
    The recent kernels use CONFIG_STRICT_DEVMEM and CONFIG_X86_PAT
    concerning the /dev/mem (/dev/kmem) so interchangeably one cannot
    figure out what exactly does it mean to access the /dev/mem if both
    CONFIG_STRICT_DEVMEM and CONFIG_X86_PAT are disabled.

    It would be more logically to remove pat_enabled variable in
    arch/x86/mm/pat.c and to make everything under CONFIG_X86_PAT define.
    The same goes for phys_mem_access_prot_allowed function (from
    arch/x86/mm/pat.c) even though CONFIG_X86_PAT is disabled.
    To make the story worse there are four implementations of
    range_is_allowed depending on how CONFIG_STRICT_DEVMEM and
    CONFIG_X86_PAT are defined.

    I see the motivation to limit the access to DRAM from root account
    CONFIG_STRICT_DEVMEM by mmap'ing /dev/[k]mem but it's easily overruled
    by simple char driver and implementing mmap of it's own totally
    bypassing all limitations.

    What do you think about it guy?
    Appreciate it.

    Felix R.

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      Last update: 2010-01-17 17:49    [W:0.021 / U:2.908 seconds]
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