31 lines
1 KiB
C
31 lines
1 KiB
C
#ifndef _M68K_SHM_H
|
|
#define _M68K_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 /* _M68K_SHM_H */
|