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Linux kernel mirror (for testing)
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linux
1#ifndef _H8300_SHM_H
2#define _H8300_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 /* _H8300_SHM_H */