diff options
Diffstat (limited to 'arch/m68k/include/asm/shm.h')
-rw-r--r-- | arch/m68k/include/asm/shm.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/m68k/include/asm/shm.h b/arch/m68k/include/asm/shm.h new file mode 100644 index 000000000000..fa56ec84a126 --- /dev/null +++ b/arch/m68k/include/asm/shm.h | |||
@@ -0,0 +1,31 @@ | |||
1 | #ifndef _M68K_SHM_H | ||
2 | #define _M68K_SHM_H | ||
3 | |||
4 | |||
5 | /* format of page table entries that correspond to shared memory pages | ||
6 | currently out in swap space (see also mm/swap.c): | ||
7 | bits 0-1 (PAGE_PRESENT) is = 0 | ||
8 | bits 8..2 (SWP_TYPE) are = SHM_SWP_TYPE | ||
9 | bits 31..9 are used like this: | ||
10 | bits 15..9 (SHM_ID) the id of the shared memory segment | ||
11 | bits 30..16 (SHM_IDX) the index of the page within the shared memory segment | ||
12 | (actually only bits 25..16 get used since SHMMAX is so low) | ||
13 | bit 31 (SHM_READ_ONLY) flag whether the page belongs to a read-only attach | ||
14 | */ | ||
15 | /* on the m68k both bits 0 and 1 must be zero */ | ||
16 | /* format on the sun3 is similar, but bits 30, 31 are set to zero and all | ||
17 | others are reduced by 2. --m */ | ||
18 | |||
19 | #ifndef CONFIG_SUN3 | ||
20 | #define SHM_ID_SHIFT 9 | ||
21 | #else | ||
22 | #define SHM_ID_SHIFT 7 | ||
23 | #endif | ||
24 | #define _SHM_ID_BITS 7 | ||
25 | #define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1) | ||
26 | |||
27 | #define SHM_IDX_SHIFT (SHM_ID_SHIFT+_SHM_ID_BITS) | ||
28 | #define _SHM_IDX_BITS 15 | ||
29 | #define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1) | ||
30 | |||
31 | #endif /* _M68K_SHM_H */ | ||