Source to sys/param.h
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* @(#)param.h 8.1 (Berkeley) 6/2/93
#define BSD 199306 /* System version (year & month). */
#define BSD4_3 1
#define BSD4_4 1
#define NULL 0
* Machine-independent constants (some used in following include files).
* Redefined constants are from POSIX 1003.1 limits file.
* MAXCOMLEN should be >= sizeof(ac_comm) (see <acct.h>)
* MAXLOGNAME should be >= UT_NAMESIZE (see <utmp.h>)
#define MAXCOMLEN 16 /* max command name remembered */
#define MAXINTERP 32 /* max interpreter file name length */
#define MAXLOGNAME 12 /* max login name length */
#define MAXUPRC CHILD_MAX /* max simultaneous processes */
#define NCARGS ARG_MAX /* max bytes for an exec function */
#define NGROUPS NGROUPS_MAX /* max number groups */
#define NOFILE OPEN_MAX /* max open files per process */
#define NOGROUP 65535 /* marker for empty group set member */
#define MAXHOSTNAMELEN 256 /* max hostname size */
/* More types and definitions used throughout the kernel. */
/* Signals. */
/* Machine type dependent parameters. */
* Priorities. Note that with 32 run queues, differences less than 4 are
#define PSWP 0
#define PVM 4
#define PINOD 8
#define PRIBIO 16
#define PVFS 20
#define PZERO 22 /* No longer magic, shouldn't be here. XXX */
#define PSOCK 24
#define PWAIT 32
#define PLOCK 36
#define PPAUSE 40
#define PUSER 50
#define MAXPRI 127 /* Priorities range from 0 through MAXPRI. */
#define PRIMASK 0x0ff
#define PCATCH 0x100 /* OR'd with pri for tsleep to check signals */
#define NZERO 0 /* default "nice" */
#define NBPW sizeof(int) /* number of bytes per word (integer) */
#define CMASK 022 /* default file mask: S_IWGRP|S_IWOTH */
#define NODEV (dev_t)(-1) /* non-existent device */
* Clustering of hardware pages on machines with ridiculously small
* page sizes is done here. The paging subsystem deals with units of
* CLSIZE pte's describing NBPG (from machine/machparam.h) pages each.
#define CLBYTES (CLSIZE*NBPG)
#define CLOFSET (CLSIZE*NBPG-1) /* for clusters, like PGOFSET */
#define claligned(x) ((((int)(x))&CLOFSET)==0)
#define CLOFF CLOFSET
#define CLSHIFT (PGSHIFT+CLSIZELOG2)
#define clbase(i) (i)
#define clrnd(i) (i)
/* Give the base virtual address (first of CLSIZE). */
#define clbase(i) ((i) &~ (CLSIZE-1))
/* Round a number of clicks up to a whole cluster. */
#define clrnd(i) (((i) + (CLSIZE-1)) &~ (CLSIZE-1))
#define CBLOCK 64 /* Clist block size, must be a power of 2. */
#define CBQSIZE (CBLOCK/NBBY) /* Quote bytes/cblock - can do better. */
/* Data chars/clist. */
#define CBSIZE (CBLOCK - sizeof(struct cblock *) - CBQSIZE)
#define CROUND (CBLOCK - 1) /* Clist rounding. */
* File system parameters and macros.
* The file system is made out of blocks of at most MAXBSIZE units, with
* smaller units (fragments) only in the last direct block. MAXBSIZE
* primarily determines the size of buffers in the buffer pool. It may be
* made larger without any effect on existing file systems; however making
* it smaller make make some file systems unmountable.
#define MAXBSIZE MAXPHYS
#define MAXFRAG 8
* MAXPATHLEN defines the longest permissable path length after expanding
* symbolic links. It is used to allocate a temporary buffer from the buffer
* pool in which to do the name expansion, hence should be a power of two,
* and must be less than or equal to MAXBSIZE. MAXSYMLINKS defines the
* maximum number of symbolic links that may be expanded in a path name.
* It should be set high enough to allow all legitimate uses, but halt
* infinite loops reasonably quickly.
#define MAXPATHLEN PATH_MAX
#define MAXSYMLINKS 8
/* Bit map related macros. */
#define setbit(a,i) ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
#define clrbit(a,i) ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
#define isset(a,i) ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
#define isclr(a,i) (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
/* Macros for counting and rounding. */
#define howmany(x, y) (((x)+((y)-1))/(y))
#define roundup(x, y) ((((x)+((y)-1))/(y))*(y))
#define powerof2(x) ((((x)-1)&(x))==0)
/* Macros for min/max. */
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))
* Constants for setting the parameters of the kernel memory allocator.
* 2 ** MINBUCKET is the smallest unit of memory that will be
* allocated. It must be at least large enough to hold a pointer.
* Units of memory less or equal to MAXALLOCSAVE will permanently
* allocate physical memory; requests for these size pieces of
* memory are quite fast. Allocations greater than MAXALLOCSAVE must
* always allocate and free physical memory; requests for these
* size allocations should be done infrequently as they will be slow.
* Constraints: CLBYTES <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
* MAXALLOCSIZE must be a power of two.
#define MINBUCKET 4 /* 4 => min allocation of 16 bytes */
#define MAXALLOCSAVE (2 * CLBYTES)
* Scale factor for scaled integers used to count %cpu time and load avgs.
* The number of CPU `tick's that map to a unique `%age' can be expressed
* by the formula (1 / (2 ^ (FSHIFT - 11))). The maximum load average that
* can be calculated (assuming 32 bits) can be closely approximated using
* the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
* For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
* FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
#define FSHIFT 11 /* bits to right of fixed binary point */
#define FSCALE (1<<FSHIFT)