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 00000000000..fa56ec84a12 --- /dev/null +++ b/arch/m68k/include/asm/shm.h @@ -0,0 +1,31 @@ +#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 */ |