include/asm-alpha/shmparam.h

   1 #ifndef _ASMAXP_SHMPARAM_H
   2 #define _ASMAXP_SHMPARAM_H
   3
   4 /*
   5  * Address range for shared memory attaches if no address passed to shmat().
   6  */
   7 #define SHM_RANGE_START 0x14000000000
   8 #define SHM_RANGE_END   0x15000000000
   9
  10
  11 /*
  12  * Format of a swap-entry for shared memory pages currently out in
  13  * swap space (see also mm/swap.c).
  14  *
  15  * SWP_TYPE = SHM_SWP_TYPE
  16  * SWP_OFFSET is used as follows:
  17  *
  18  *  bits 0..6 : id of shared memory segment page belongs to (SHM_ID)
  19  *  bits 7..21: index of page within shared memory segment (SHM_IDX)
  20  *              (actually fewer bits get used since SHMMAX is so low)
  21  */
  22
  23 /*
  24  * Keep _SHM_ID_BITS as low as possible since SHMMNI depends on it and
  25  * there is a static array of size SHMMNI.
  26  */
  27 #define _SHM_ID_BITS    7
  28 #define SHM_ID_MASK     ((1<<_SHM_ID_BITS)-1)
  29
  30 #define SHM_IDX_SHIFT   (_SHM_ID_BITS)
  31 #define _SHM_IDX_BITS   15
  32 #define SHM_IDX_MASK    ((1<<_SHM_IDX_BITS)-1)
  33
  34 /*
  35  * _SHM_ID_BITS + _SHM_IDX_BITS must be <= 24 on the Alpha and
  36  * SHMMAX <= (PAGE_SIZE << _SHM_IDX_BITS).
  37  */
  38
  39 #define SHMMAX 0x3fa000                 /* max shared seg size (bytes) */
  40 #define SHMMIN 1 /* really PAGE_SIZE */ /* min shared seg size (bytes) */
  41 #define SHMMNI (1<<_SHM_ID_BITS)        /* max num of segs system wide */
  42 #define SHMALL                          /* max shm system wide (pages) */ \
  43         (1<<(_SHM_IDX_BITS+_SHM_ID_BITS))
  44 #define SHMLBA PAGE_SIZE                /* attach addr a multiple of this */
  45 #define SHMSEG SHMMNI                   /* max shared segs per process */
  46
  47 #endif /* _ASMAXP_SHMPARAM_H */