• Helge Deller's avatar
    parisc: Convert MAP_TYPE to cover 4 bits on parisc · d5b59a71
    Helge Deller authored
    On parisc we want to be as much as possible compatible to the major
    architectures like x86. Those architectures have MAP_TYPE defined as 0x0f which
    covers MAP_SHARED and MAP_PRIVATE and leaves two more bits unused.
    In contrast, on parisc we have MAP_TYPE defined to 0x03 which covers MAP_SHARED
    and MAP_PRIVATE only. But we don't have the 2 bits free as x86.
    Usually that's not a problem, but during the discussions for pmem+dax support
    the idea came up to use the two remaining bits of MAP_TYPE (on x86 and others)
    for the new MAP_DIRECT and MAP_SYNC flags. One requirement is, that an old
    kernel should correctly handle MAP_DIRECT and MAP_SYNC and fail on those if
    set. This only works if MAP_TYPE has 4 bits.
    Even though the pmem+dax people now choosed another solution via
    MAP_SHARED_VALIDATE, let's still proceed to be more compatible to x86 by adding
    two more bits for future usage.
    Signed-off-by: default avatarHelge Deller <deller@gmx.de>
    Signed-off-by: default avatarJohn David Anglin <dave.anglin@bell.net>
mman.h 3.39 KB