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: releng/5.2/sys/sys/param.h 126150 2004-02-23 05:34:20Z scottl $
   40  */
   41 
   42 #ifndef _SYS_PARAM_H_
   43 #define _SYS_PARAM_H_
   44 
   45 #include <sys/_null.h>
   46 
   47 #define BSD     199506          /* System version (year & month). */
   48 #define BSD4_3  1
   49 #define BSD4_4  1
   50 
   51 /* 
   52  * __FreeBSD_version numbers are documented in the Porter's Handbook.
   53  * If you bump the version for any reason, you should update the documentation
   54  * there.
   55  * Currently this lives here:
   56  *
   57  *      doc/en_US.ISO8859-1/books/porters-handbook/book.sgml
   58  *
   59  * scheme is:  <major><two digit minor><0 if release branch, otherwise 1>xx
   60  */
   61 #undef __FreeBSD_version
   62 #define __FreeBSD_version 502010        /* Master, propagated to newvers */
   63 
   64 #ifndef LOCORE
   65 #include <sys/types.h>
   66 #endif
   67 
   68 /*
   69  * Machine-independent constants (some used in following include files).
   70  * Redefined constants are from POSIX 1003.1 limits file.
   71  *
   72  * MAXCOMLEN should be >= sizeof(ac_comm) (see <acct.h>)
   73  * MAXLOGNAME should be == UT_NAMESIZE+1 (see <utmp.h>)
   74  */
   75 #include <sys/syslimits.h>
   76 
   77 #define MAXCOMLEN       19              /* max command name remembered */
   78 #define MAXINTERP       32              /* max interpreter file name length */
   79 #define MAXLOGNAME      17              /* max login name length (incl. NUL) */
   80 #define MAXUPRC         CHILD_MAX       /* max simultaneous processes */
   81 #define NCARGS          ARG_MAX         /* max bytes for an exec function */
   82 #define NGROUPS         NGROUPS_MAX     /* max number groups */
   83 #define NOFILE          OPEN_MAX        /* max open files per process */
   84 #define NOGROUP         65535           /* marker for empty group set member */
   85 #define MAXHOSTNAMELEN  256             /* max hostname size */
   86 #define SPECNAMELEN     63              /* max length of devicename */
   87 
   88 /* More types and definitions used throughout the kernel. */
   89 #ifdef _KERNEL
   90 #if (defined(BURN_BRIDGES) || __FreeBSD_version >= 600000) \
   91         && defined(OBSOLETE_IN_6)
   92 #error "This file contains obsolete code to be removed in 6.0-current"
   93 #endif
   94 #include <sys/cdefs.h>
   95 #include <sys/errno.h>
   96 #include <sys/time.h>
   97 #include <sys/priority.h>
   98 
   99 #define FALSE   0
  100 #define TRUE    1
  101 #endif
  102 
  103 #ifndef _KERNEL
  104 /* Signals. */
  105 #include <sys/signal.h>
  106 #endif
  107 
  108 /* Machine type dependent parameters. */
  109 #include <machine/param.h>
  110 #ifndef _KERNEL
  111 #include <sys/limits.h>
  112 #endif
  113 
  114 #ifndef _NO_NAMESPACE_POLLUTION
  115 
  116 #ifndef DEV_BSHIFT
  117 #define DEV_BSHIFT      9               /* log2(DEV_BSIZE) */
  118 #endif
  119 #define DEV_BSIZE       (1<<DEV_BSHIFT)
  120 
  121 #ifndef BLKDEV_IOSIZE
  122 #define BLKDEV_IOSIZE  PAGE_SIZE        /* default block device I/O size */
  123 #endif
  124 #ifndef DFLTPHYS
  125 #define DFLTPHYS        (64 * 1024)     /* default max raw I/O transfer size */
  126 #endif
  127 #ifndef MAXPHYS
  128 #define MAXPHYS         (128 * 1024)    /* max raw I/O transfer size */
  129 #endif
  130 #ifndef MAXDUMPPGS
  131 #define MAXDUMPPGS      (DFLTPHYS/PAGE_SIZE)
  132 #endif
  133 
  134 /*
  135  * Constants related to network buffer management.
  136  * MCLBYTES must be no larger than PAGE_SIZE.
  137  */
  138 #ifndef MSIZE
  139 #define MSIZE           256             /* size of an mbuf */
  140 #endif  /* MSIZE */
  141 
  142 #ifndef MCLSHIFT
  143 #define MCLSHIFT        11              /* convert bytes to mbuf clusters */
  144 #endif  /* MCLSHIFT */
  145 
  146 #define MCLBYTES        (1 << MCLSHIFT) /* size of an mbuf cluster */
  147 
  148 /*
  149  * Some macros for units conversion
  150  */
  151 
  152 /* clicks to bytes */
  153 #ifndef ctob
  154 #define ctob(x) ((x)<<PAGE_SHIFT)
  155 #endif
  156 
  157 /* bytes to clicks */
  158 #ifndef btoc
  159 #define btoc(x) (((vm_offset_t)(x)+PAGE_MASK)>>PAGE_SHIFT)
  160 #endif
  161 
  162 /*
  163  * btodb() is messy and perhaps slow because `bytes' may be an off_t.  We
  164  * want to shift an unsigned type to avoid sign extension and we don't
  165  * want to widen `bytes' unnecessarily.  Assume that the result fits in
  166  * a daddr_t.
  167  */
  168 #ifndef btodb
  169 #define btodb(bytes)                    /* calculates (bytes / DEV_BSIZE) */ \
  170         (sizeof (bytes) > sizeof(long) \
  171          ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
  172          : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))
  173 #endif
  174 
  175 #ifndef dbtob
  176 #define dbtob(db)                       /* calculates (db * DEV_BSIZE) */ \
  177         ((off_t)(db) << DEV_BSHIFT)
  178 #endif
  179 
  180 #endif /* _NO_NAMESPACE_POLLUTION */
  181 
  182 #define PRIMASK 0x0ff
  183 #define PCATCH  0x100           /* OR'd with pri for tsleep to check signals */
  184 #define PDROP   0x200   /* OR'd with pri to stop re-entry of interlock mutex */
  185 
  186 #define NZERO   0               /* default "nice" */
  187 
  188 #define NBBY    8               /* number of bits in a byte */
  189 #define NBPW    sizeof(int)     /* number of bytes per word (integer) */
  190 
  191 #define CMASK   022             /* default file mask: S_IWGRP|S_IWOTH */
  192 #define NODEV   (dev_t)(-1)     /* non-existent device */
  193 #ifdef _KERNEL
  194 #define NOUDEV  (udev_t)(-1)    /* non-existent device */
  195 #define NOMAJ   256             /* non-existent device */
  196 #endif
  197 
  198 #define CBLOCK  128             /* Clist block size, must be a power of 2. */
  199 #define CBQSIZE (CBLOCK/NBBY)   /* Quote bytes/cblock - can do better. */
  200                                 /* Data chars/clist. */
  201 #define CBSIZE  (CBLOCK - sizeof(struct cblock *) - CBQSIZE)
  202 #define CROUND  (CBLOCK - 1)    /* Clist rounding. */
  203 
  204 /*
  205  * File system parameters and macros.
  206  *
  207  * MAXBSIZE -   Filesystems are made out of blocks of at most MAXBSIZE bytes
  208  *              per block.  MAXBSIZE may be made larger without effecting
  209  *              any existing filesystems as long as it does not exceed MAXPHYS,
  210  *              and may be made smaller at the risk of not being able to use
  211  *              filesystems which require a block size exceeding MAXBSIZE.
  212  *
  213  * BKVASIZE -   Nominal buffer space per buffer, in bytes.  BKVASIZE is the
  214  *              minimum KVM memory reservation the kernel is willing to make.
  215  *              Filesystems can of course request smaller chunks.  Actual 
  216  *              backing memory uses a chunk size of a page (PAGE_SIZE).
  217  *
  218  *              If you make BKVASIZE too small you risk seriously fragmenting
  219  *              the buffer KVM map which may slow things down a bit.  If you
  220  *              make it too big the kernel will not be able to optimally use 
  221  *              the KVM memory reserved for the buffer cache and will wind 
  222  *              up with too-few buffers.
  223  *
  224  *              The default is 16384, roughly 2x the block size used by a
  225  *              normal UFS filesystem.
  226  */
  227 #define MAXBSIZE        65536   /* must be power of 2 */
  228 #define BKVASIZE        16384   /* must be power of 2 */
  229 #define BKVAMASK        (BKVASIZE-1)
  230 
  231 /*
  232  * MAXPATHLEN defines the longest permissible path length after expanding
  233  * symbolic links. It is used to allocate a temporary buffer from the buffer
  234  * pool in which to do the name expansion, hence should be a power of two,
  235  * and must be less than or equal to MAXBSIZE.  MAXSYMLINKS defines the
  236  * maximum number of symbolic links that may be expanded in a path name.
  237  * It should be set high enough to allow all legitimate uses, but halt
  238  * infinite loops reasonably quickly.
  239  */
  240 #define MAXPATHLEN      PATH_MAX
  241 #define MAXSYMLINKS     32
  242 
  243 /* Bit map related macros. */
  244 #define setbit(a,i)     ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
  245 #define clrbit(a,i)     ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
  246 #define isset(a,i)      ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
  247 #define isclr(a,i)      (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
  248 
  249 /* Macros for counting and rounding. */
  250 #ifndef howmany
  251 #define howmany(x, y)   (((x)+((y)-1))/(y))
  252 #endif
  253 #define rounddown(x, y) (((x)/(y))*(y))
  254 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))  /* to any y */
  255 #define roundup2(x, y)  (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
  256 #define powerof2(x)     ((((x)-1)&(x))==0)
  257 
  258 /* Macros for min/max. */
  259 #define MIN(a,b) (((a)<(b))?(a):(b))
  260 #define MAX(a,b) (((a)>(b))?(a):(b))
  261 
  262 #ifdef _KERNEL
  263 /*
  264  * Basic byte order function prototypes for non-inline functions.
  265  */
  266 #ifndef _BYTEORDER_PROTOTYPED
  267 #define _BYTEORDER_PROTOTYPED
  268 __BEGIN_DECLS
  269 __uint32_t       htonl(__uint32_t);
  270 __uint16_t       htons(__uint16_t);
  271 __uint32_t       ntohl(__uint32_t);
  272 __uint16_t       ntohs(__uint16_t);
  273 __END_DECLS
  274 #endif
  275 
  276 #ifndef lint
  277 #ifndef _BYTEORDER_FUNC_DEFINED
  278 #define _BYTEORDER_FUNC_DEFINED
  279 #define htonl(x)        __htonl(x)
  280 #define htons(x)        __htons(x)
  281 #define ntohl(x)        __ntohl(x)
  282 #define ntohs(x)        __ntohs(x)
  283 #endif /* !_BYTEORDER_FUNC_DEFINED */
  284 #endif /* lint */
  285 #endif /* _KERNEL */
  286 
  287 /*
  288  * Constants for setting the parameters of the kernel memory allocator.
  289  *
  290  * 2 ** MINBUCKET is the smallest unit of memory that will be
  291  * allocated. It must be at least large enough to hold a pointer.
  292  *
  293  * Units of memory less or equal to MAXALLOCSAVE will permanently
  294  * allocate physical memory; requests for these size pieces of
  295  * memory are quite fast. Allocations greater than MAXALLOCSAVE must
  296  * always allocate and free physical memory; requests for these
  297  * size allocations should be done infrequently as they will be slow.
  298  *
  299  * Constraints: PAGE_SIZE <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
  300  * MAXALLOCSIZE must be a power of two.
  301  */
  302 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
  303 #define MINBUCKET       5               /* 5 => min allocation of 32 bytes */
  304 #else
  305 #define MINBUCKET       4               /* 4 => min allocation of 16 bytes */
  306 #endif
  307 #define MAXALLOCSAVE    (2 * PAGE_SIZE)
  308 
  309 /*
  310  * Scale factor for scaled integers used to count %cpu time and load avgs.
  311  *
  312  * The number of CPU `tick's that map to a unique `%age' can be expressed
  313  * by the formula (1 / (2 ^ (FSHIFT - 11))).  The maximum load average that
  314  * can be calculated (assuming 32 bits) can be closely approximated using
  315  * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
  316  *
  317  * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
  318  * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
  319  */
  320 #define FSHIFT  11              /* bits to right of fixed binary point */
  321 #define FSCALE  (1<<FSHIFT)
  322 
  323 #define dbtoc(db)                       /* calculates devblks to pages */ \
  324         ((db + (ctodb(1) - 1)) >> (PAGE_SHIFT - DEV_BSHIFT))
  325  
  326 #define ctodb(db)                       /* calculates pages to devblks */ \
  327         ((db) << (PAGE_SHIFT - DEV_BSHIFT))
  328 
  329 #endif  /* _SYS_PARAM_H_ */

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