Commit | Line | Data |
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1da177e4 LT |
1 | #ifndef _M68K_SHM_H |
2 | #define _M68K_SHM_H | |
3 | ||
1da177e4 LT |
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 */ |