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- #ifndef _H8300_SHM_H
- #define _H8300_SHM_H
- /* format of page table entries that correspond to shared memory pages
- currently out in swap space (see also mm/swap.c):
- bits 0-1 (PAGE_PRESENT) is = 0
- bits 8..2 (SWP_TYPE) are = SHM_SWP_TYPE
- bits 31..9 are used like this:
- bits 15..9 (SHM_ID) the id of the shared memory segment
- bits 30..16 (SHM_IDX) the index of the page within the shared memory segment
- (actually only bits 25..16 get used since SHMMAX is so low)
- bit 31 (SHM_READ_ONLY) flag whether the page belongs to a read-only attach
- */
- /* on the m68k both bits 0 and 1 must be zero */
- /* format on the sun3 is similar, but bits 30, 31 are set to zero and all
- others are reduced by 2. --m */
- #ifndef CONFIG_SUN3
- #define SHM_ID_SHIFT 9
- #else
- #define SHM_ID_SHIFT 7
- #endif
- #define _SHM_ID_BITS 7
- #define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1)
- #define SHM_IDX_SHIFT (SHM_ID_SHIFT+_SHM_ID_BITS)
- #define _SHM_IDX_BITS 15
- #define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1)
- #endif /* _H8300_SHM_H */
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