FreeBSD/Linux Kernel Cross Reference
sys/sys/param.h

     /*-
      * Copyright (c) 1982, 1986, 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)param.h     8.3 (Berkeley) 4/4/95
     * $FreeBSD: src/sys/sys/param.h,v 1.15.2.4 1999/09/05 08:22:43 peter Exp $
     */
    
    #ifndef _SYS_PARAM_H_
    #define _SYS_PARAM_H_
    
    #define BSD     199506          /* System version (year & month). */
    #define BSD4_3  1
    #define BSD4_4  1
    
    #ifndef NULL
    #define NULL    0
    #endif
    
    #ifndef LOCORE
    #include <sys/types.h>
    #endif
    
    /*
     * 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>)
     */
    #include <sys/syslimits.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. */
    #ifdef KERNEL
    #include <sys/cdefs.h>
    #include <sys/errno.h>
    #include <sys/time.h>
    #include <sys/resource.h>
    #include <sys/ucred.h>
    #include <sys/uio.h>
    #include <sys/rtprio.h>
    
    #define FALSE   0
    #define TRUE    1
    #endif
    
    /* Signals. */
    #include <sys/signal.h>
    
    /* Machine type dependent parameters. */
    #include <machine/param.h>
    #include <machine/limits.h>
    
    /*
     * Priorities.  Note that with 32 run queues, differences less than 4 are
     * insignificant.
    */
   #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 PCONFIG 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 PAGE_SIZE (from machine/machparam.h) pages each.
    */
   #if 0
   #define CLBYTES         (CLSIZE*PAGE_SIZE)
   #endif
   
   #define CBLOCK  128             /* 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.  Also, MAXBSIZE
    * must be less than MAXPHYS!!!  DFLTBSIZE is the average amount of
    * memory allocated by vfs_bio per nbuf.  BKVASIZE is the average amount
    * of kernel virtual space allocated per nbuf.  BKVASIZE should be >=
    * DFLTBSIZE.  If it is significantly bigger than DFLTBSIZE, then
    * kva fragmentation causes fewer performance problems.
    */
   #define MAXBSIZE        65536
   #define BKVASIZE        8192
   #define DFLTBSIZE       4096
   #define MAXFRAG         8
   
   /*
    * MAXPATHLEN defines the longest permissible 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     32
   
   /* 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. */
   #ifndef howmany
   #define howmany(x, y)   (((x)+((y)-1))/(y))
   #endif
   #define rounddown(x, y) (((x)/(y))*(y))
   #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))  /* to any y */
   #define roundup2(x, y)  (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
   #define powerof2(x)     ((((x)-1)&(x))==0)
   
   /* Macros for min/max. */
   #ifndef KERNEL
   #define MIN(a,b) (((a)<(b))?(a):(b))
   #define MAX(a,b) (((a)>(b))?(a):(b))
   #endif
   
   /*
    * 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: PAGE_SIZE <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
    * MAXALLOCSIZE must be a power of two.
    */
   #define MINBUCKET       4               /* 4 => min allocation of 16 bytes */
   #define MAXALLOCSAVE    (2 * PAGE_SIZE)
   
   /*
    * 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)
   
   #endif  /* _SYS_PARAM_H_ */

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