usr/src/sys/h/vmparam.h

/*      vmparam.h       4.1     11/9/80 */

/*
 * Machine dependent constants
 */
#define NBBY            8               /* number of bits in a byte */
#define NBPG            512             /* number of bytes per page */
#define PGSHIFT         9               /* LOG2(NBPG) */
#define NPTEPG          (NBPG/(sizeof (struct pte)))
                                        /* number of ptes per page */
#define PGOFSET         (NBPG-1)        /* byte offset into page */
#define CLOFSET         (CLSIZE*NBPG-1) /* for clusters, like PGOFSET */
#define USRSTACK        (0x80000000-UPAGES*NBPG)
                                        /* Start of user stack */
#define P1TOP           0x200000        /* boundary between P0 and P1 regions */
#define AST             0x04000000      /* ast level */

/*
 * Virtual memory related constants
 *
 * note: USRPTSIZE is well known in locore.s
 */
#define SLOP    16
#define MAXTSIZ         (6*2048-SLOP)           /* max text size (clicks) */
#define MAXDSIZ         (11*1024-16-SLOP)       /* max data size (clicks) */
#define MAXSSIZ         (11*1024-16-SLOP)       /* max stack size (clicks) */
#define USRPTSIZE       (8*NPTEPG)      /* max number of pages of page tables
                                           for resident processes, this is
                                           known in locore.s */