The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by the University of
   21  *      California, Berkeley and its contributors.
   22  * 4. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      @(#)param.h     8.3 (Berkeley) 4/4/95
   39  * $FreeBSD$
   40  */
   41 
   42 #ifndef _SYS_PARAM_H_
   43 #define _SYS_PARAM_H_
   44 
   45 #define BSD     199506          /* System version (year & month). */
   46 #define BSD4_3  1
   47 #define BSD4_4  1
   48 #undef __FreeBSD_version
   49 #define __FreeBSD_version 350001        /* Master, propagated to newvers */
   50 
   51 #ifndef NULL
   52 #define NULL    0
   53 #endif
   54 
   55 #ifndef LOCORE
   56 #include <sys/types.h>
   57 #endif
   58 
   59 /*
   60  * Machine-independent constants (some used in following include files).
   61  * Redefined constants are from POSIX 1003.1 limits file.
   62  *
   63  * MAXCOMLEN should be >= sizeof(ac_comm) (see <acct.h>)
   64  * MAXLOGNAME should be == UT_NAMESIZE+1 (see <utmp.h>)
   65  */
   66 #include <sys/syslimits.h>
   67 
   68 #define MAXCOMLEN       16              /* max command name remembered */
   69 #define MAXINTERP       32              /* max interpreter file name length */
   70 #define MAXLOGNAME      17              /* max login name length (incl. NUL) */
   71 #define MAXUPRC         CHILD_MAX       /* max simultaneous processes */
   72 #define NCARGS          ARG_MAX         /* max bytes for an exec function */
   73 #define NGROUPS         NGROUPS_MAX     /* max number groups */
   74 #define NOFILE          OPEN_MAX        /* max open files per process */
   75 #define NOGROUP         65535           /* marker for empty group set member */
   76 #define MAXHOSTNAMELEN  256             /* max hostname size */
   77 
   78 /* More types and definitions used throughout the kernel. */
   79 #ifdef KERNEL
   80 #include <sys/cdefs.h>
   81 #include <sys/errno.h>
   82 #include <sys/time.h>
   83 
   84 #define FALSE   0
   85 #define TRUE    1
   86 #endif
   87 
   88 #ifndef KERNEL
   89 /* Signals. */
   90 #include <sys/signal.h>
   91 #endif
   92 
   93 /* Machine type dependent parameters. */
   94 #include <machine/param.h>
   95 #ifndef KERNEL
   96 #include <machine/limits.h>
   97 #endif
   98 
   99 /*
  100  * Priorities.  Note that with 32 run queues, differences less than 4 are
  101  * insignificant.
  102  */
  103 #define PSWP    0
  104 #define PVM     4
  105 #define PINOD   8
  106 #define PRIBIO  16
  107 #define PVFS    20
  108 #define PZERO   22              /* No longer magic, shouldn't be here.  XXX */
  109 #define PSOCK   24
  110 #define PWAIT   32
  111 #define PCONFIG 32
  112 #define PLOCK   36
  113 #define PPAUSE  40
  114 #define PUSER   50
  115 #define MAXPRI  127             /* Priorities range from 0 through MAXPRI. */
  116 
  117 #define PRIMASK 0x0ff
  118 #define PCATCH  0x100           /* OR'd with pri for tsleep to check signals */
  119 
  120 #define NZERO   0               /* default "nice" */
  121 
  122 #define NBPW    sizeof(int)     /* number of bytes per word (integer) */
  123 
  124 #define CMASK   022             /* default file mask: S_IWGRP|S_IWOTH */
  125 #define NODEV   (dev_t)(-1)     /* non-existent device */
  126 
  127 /*
  128  * Clustering of hardware pages on machines with ridiculously small
  129  * page sizes is done here.  The paging subsystem deals with units of
  130  * CLSIZE pte's describing PAGE_SIZE (from machine/machparam.h) pages each.
  131  */
  132 #if 0
  133 #define CLBYTES         (CLSIZE*PAGE_SIZE)
  134 #endif
  135 
  136 #define CBLOCK  128             /* Clist block size, must be a power of 2. */
  137 #define CBQSIZE (CBLOCK/NBBY)   /* Quote bytes/cblock - can do better. */
  138                                 /* Data chars/clist. */
  139 #define CBSIZE  (CBLOCK - sizeof(struct cblock *) - CBQSIZE)
  140 #define CROUND  (CBLOCK - 1)    /* Clist rounding. */
  141 
  142 /*
  143  * File system parameters and macros.
  144  *
  145  * The file system is made out of blocks of at most MAXBSIZE units, with
  146  * smaller units (fragments) only in the last direct block.  MAXBSIZE
  147  * primarily determines the size of buffers in the buffer pool.  It may be
  148  * made larger without any effect on existing file systems; however making
  149  * it smaller make make some file systems unmountable.  Also, MAXBSIZE
  150  * must be less than MAXPHYS!!!  DFLTBSIZE is the average amount of
  151  * memory allocated by vfs_bio per nbuf.  BKVASIZE is the average amount
  152  * of kernel virtual space allocated per nbuf.  BKVASIZE should be >=
  153  * DFLTBSIZE.  If it is significantly bigger than DFLTBSIZE, then
  154  * kva fragmentation causes fewer performance problems.
  155  */
  156 #define MAXBSIZE        65536
  157 #define BKVASIZE        8192
  158 #define DFLTBSIZE       4096
  159 #define MAXFRAG         8
  160 
  161 /*
  162  * MAXPATHLEN defines the longest permissible path length after expanding
  163  * symbolic links. It is used to allocate a temporary buffer from the buffer
  164  * pool in which to do the name expansion, hence should be a power of two,
  165  * and must be less than or equal to MAXBSIZE.  MAXSYMLINKS defines the
  166  * maximum number of symbolic links that may be expanded in a path name.
  167  * It should be set high enough to allow all legitimate uses, but halt
  168  * infinite loops reasonably quickly.
  169  */
  170 #define MAXPATHLEN      PATH_MAX
  171 #define MAXSYMLINKS     32
  172 
  173 /* Bit map related macros. */
  174 #define setbit(a,i)     ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
  175 #define clrbit(a,i)     ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
  176 #define isset(a,i)      ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
  177 #define isclr(a,i)      (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
  178 
  179 /* Macros for counting and rounding. */
  180 #ifndef howmany
  181 #define howmany(x, y)   (((x)+((y)-1))/(y))
  182 #endif
  183 #define rounddown(x, y) (((x)/(y))*(y))
  184 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))  /* to any y */
  185 #define roundup2(x, y)  (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
  186 #define powerof2(x)     ((((x)-1)&(x))==0)
  187 
  188 /* Macros for min/max. */
  189 #ifndef KERNEL
  190 #define MIN(a,b) (((a)<(b))?(a):(b))
  191 #define MAX(a,b) (((a)>(b))?(a):(b))
  192 #endif
  193 
  194 /*
  195  * Constants for setting the parameters of the kernel memory allocator.
  196  *
  197  * 2 ** MINBUCKET is the smallest unit of memory that will be
  198  * allocated. It must be at least large enough to hold a pointer.
  199  *
  200  * Units of memory less or equal to MAXALLOCSAVE will permanently
  201  * allocate physical memory; requests for these size pieces of
  202  * memory are quite fast. Allocations greater than MAXALLOCSAVE must
  203  * always allocate and free physical memory; requests for these
  204  * size allocations should be done infrequently as they will be slow.
  205  *
  206  * Constraints: PAGE_SIZE <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
  207  * MAXALLOCSIZE must be a power of two.
  208  */
  209 #if defined(__alpha__)
  210 #define MINBUCKET       5               /* 5 => min allocation of 32 bytes */
  211 #else
  212 #define MINBUCKET       4               /* 4 => min allocation of 16 bytes */
  213 #endif
  214 #define MAXALLOCSAVE    (2 * PAGE_SIZE)
  215 
  216 /*
  217  * Scale factor for scaled integers used to count %cpu time and load avgs.
  218  *
  219  * The number of CPU `tick's that map to a unique `%age' can be expressed
  220  * by the formula (1 / (2 ^ (FSHIFT - 11))).  The maximum load average that
  221  * can be calculated (assuming 32 bits) can be closely approximated using
  222  * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
  223  *
  224  * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
  225  * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
  226  */
  227 #define FSHIFT  11              /* bits to right of fixed binary point */
  228 #define FSCALE  (1<<FSHIFT)
  229 
  230 #endif  /* _SYS_PARAM_H_ */

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