include/asm-sparc/shmparam.h

   1 /* $Id: shmparam.h,v 1.4 1998/09/28 07:15:01 jj Exp $ */
   2 #ifndef _ASMSPARC_SHMPARAM_H
   3 #define _ASMSPARC_SHMPARAM_H
   4
   5 /* address range for shared memory attaches if no address passed to shmat() */
   6 #define SHM_RANGE_START 0x10000000
   7 #define SHM_RANGE_END   0x20000000
   8
   9 /*
  10  * Format of a swap-entry for shared memory pages currently out in
  11  * swap space (see also mm/swap.c).
  12  *
  13  * SWP_TYPE = SHM_SWP_TYPE
  14  * SWP_OFFSET is used as follows:
  15  *
  16  *  bits 0..6 : id of shared memory segment page belongs to (SHM_ID)
  17  *  bits 7..21: index of page within shared memory segment (SHM_IDX)
  18  *              (actually fewer bits get used since SHMMAX is so low)
  19  */
  20
  21 /*
  22  * Keep _SHM_ID_BITS as low as possible since SHMMNI depends on it and
  23  * there is a static array of size SHMMNI.
  24  */
  25 #define _SHM_ID_BITS    7
  26 #define SHM_ID_MASK     ((1<<_SHM_ID_BITS)-1)
  27
  28 #define SHM_IDX_SHIFT   (_SHM_ID_BITS)
  29 #define _SHM_IDX_BITS   15
  30 #define SHM_IDX_MASK    ((1<<_SHM_IDX_BITS)-1)
  31
  32 /*
  33  * _SHM_ID_BITS + _SHM_IDX_BITS must be <= 24 on the i386 and
  34  * SHMMAX <= (PAGE_SIZE << _SHM_IDX_BITS).
  35  */
  36
  37 #define SHMMAX 0x1000000                /* max shared seg size (bytes) */
  38 #define SHMMIN 1 /* really PAGE_SIZE */ /* min shared seg size (bytes) */
  39 #define SHMMNI (1<<_SHM_ID_BITS)        /* max num of segs system wide */
  40 #define SHMALL                          /* max shm system wide (pages) */ \
  41         (1<<(_SHM_IDX_BITS+_SHM_ID_BITS))
  42 #define SHMLBA PAGE_SIZE                /* attach addr a multiple of this */
  43 #define SHMSEG SHMMNI                   /* max shared segs per process */
  44
  45 #endif /* _ASMSPARC_SHMPARAM_H */