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parisc: Convert MAP_TYPE to cover 4 bits on parisc

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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: Helge Deller <deller@gmx.de>
Signed-off-by: John David Anglin <dave.anglin@bell.net>
This commit is contained in:
Helge Deller 2017-09-26 00:21:27 +02:00
parent 184b922cb6
commit d5b59a7120
1 changed files with 1 additions and 1 deletions
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2
arch/parisc/include/uapi/asm/mman.h
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@ -13,7 +13,7 @@
#define MAP_SHARED 0x01 /* Share changes */
#define MAP_PRIVATE 0x02 /* Changes are private */
#define MAP_SHARED_VALIDATE 0x03 /* share + validate extension flags */
#define MAP_TYPE 0x03 /* Mask for type of mapping */
#define MAP_TYPE 0x2b /* Mask for type of mapping, includes bits 0x08 and 0x20 */
#define MAP_FIXED 0x04 /* Interpret addr exactly */
#define MAP_ANONYMOUS 0x10 /* don't use a file */