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  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)param.h     8.3 (Berkeley) 4/4/95
   35  * $FreeBSD: releng/9.2/sys/sys/param.h 253912 2013-08-03 12:41:21Z gjb $
   36  */
   37 
   38 #ifndef _SYS_PARAM_H_
   39 #define _SYS_PARAM_H_
   40 
   41 #include <sys/_null.h>
   42 
   43 #define BSD     199506          /* System version (year & month). */
   44 #define BSD4_3  1
   45 #define BSD4_4  1
   46 
   47 /* 
   48  * __FreeBSD_version numbers are documented in the Porter's Handbook.
   49  * If you bump the version for any reason, you should update the documentation
   50  * there.
   51  * Currently this lives here in the doc/ repository:
   52  *
   53  *      head/en_US.ISO8859-1/books/porters-handbook/book.xml
   54  *
   55  * scheme is:  <major><two digit minor>Rxx
   56  *              'R' is in the range 0 to 4 if this is a release branch or
   57  *              x.0-CURRENT before RELENG_*_0 is created, otherwise 'R' is
   58  *              in the range 5 to 9.
   59  */
   60 #undef __FreeBSD_version
   61 #define __FreeBSD_version 902001        /* Master, propagated to newvers */
   62 
   63 /*
   64  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
   65  * which by definition is always true on FreeBSD. This macro is also defined
   66  * on other systems that use the kernel of FreeBSD, such as GNU/kFreeBSD.
   67  *
   68  * It is tempting to use this macro in userland code when we want to enable
   69  * kernel-specific routines, and in fact it's fine to do this in code that
   70  * is part of FreeBSD itself.  However, be aware that as presence of this
   71  * macro is still not widespread (e.g. older FreeBSD versions, 3rd party
   72  * compilers, etc), it is STRONGLY DISCOURAGED to check for this macro in
   73  * external applications without also checking for __FreeBSD__ as an
   74  * alternative.
   75  */
   76 #undef __FreeBSD_kernel__
   77 #define __FreeBSD_kernel__
   78 
   79 #ifdef _KERNEL
   80 #define P_OSREL_SIGWAIT         700000
   81 #define P_OSREL_SIGSEGV         700004
   82 #define P_OSREL_MAP_ANON        800104
   83 #endif
   84 
   85 #ifndef LOCORE
   86 #include <sys/types.h>
   87 #endif
   88 
   89 /*
   90  * Machine-independent constants (some used in following include files).
   91  * Redefined constants are from POSIX 1003.1 limits file.
   92  *
   93  * MAXCOMLEN should be >= sizeof(ac_comm) (see <acct.h>)
   94  */
   95 #include <sys/syslimits.h>
   96 
   97 #define MAXCOMLEN       19              /* max command name remembered */
   98 #define MAXINTERP       PATH_MAX        /* max interpreter file name length */
   99 #define MAXLOGNAME      17              /* max login name length (incl. NUL) */
  100 #define MAXUPRC         CHILD_MAX       /* max simultaneous processes */
  101 #define NCARGS          ARG_MAX         /* max bytes for an exec function */
  102 #define NGROUPS         (NGROUPS_MAX+1) /* max number groups */
  103 #define NOFILE          OPEN_MAX        /* max open files per process */
  104 #define NOGROUP         65535           /* marker for empty group set member */
  105 #define MAXHOSTNAMELEN  256             /* max hostname size */
  106 #define SPECNAMELEN     63              /* max length of devicename */
  107 
  108 /* More types and definitions used throughout the kernel. */
  109 #ifdef _KERNEL
  110 #include <sys/cdefs.h>
  111 #include <sys/errno.h>
  112 #ifndef LOCORE
  113 #include <sys/time.h>
  114 #include <sys/priority.h>
  115 #endif
  116 
  117 #ifndef FALSE
  118 #define FALSE   0
  119 #endif
  120 #ifndef TRUE
  121 #define TRUE    1
  122 #endif
  123 #endif
  124 
  125 #ifndef _KERNEL
  126 /* Signals. */
  127 #include <sys/signal.h>
  128 #endif
  129 
  130 /* Machine type dependent parameters. */
  131 #include <machine/param.h>
  132 #ifndef _KERNEL
  133 #include <sys/limits.h>
  134 #endif
  135 
  136 #ifndef DEV_BSHIFT
  137 #define DEV_BSHIFT      9               /* log2(DEV_BSIZE) */
  138 #endif
  139 #define DEV_BSIZE       (1<<DEV_BSHIFT)
  140 
  141 #ifndef BLKDEV_IOSIZE
  142 #define BLKDEV_IOSIZE  PAGE_SIZE        /* default block device I/O size */
  143 #endif
  144 #ifndef DFLTPHYS
  145 #define DFLTPHYS        (64 * 1024)     /* default max raw I/O transfer size */
  146 #endif
  147 #ifndef MAXPHYS
  148 #define MAXPHYS         (128 * 1024)    /* max raw I/O transfer size */
  149 #endif
  150 #ifndef MAXDUMPPGS
  151 #define MAXDUMPPGS      (DFLTPHYS/PAGE_SIZE)
  152 #endif
  153 
  154 /*
  155  * Constants related to network buffer management.
  156  * MCLBYTES must be no larger than PAGE_SIZE.
  157  */
  158 #ifndef MSIZE
  159 #define MSIZE           256             /* size of an mbuf */
  160 #endif  /* MSIZE */
  161 
  162 #ifndef MCLSHIFT
  163 #define MCLSHIFT        11              /* convert bytes to mbuf clusters */
  164 #endif  /* MCLSHIFT */
  165 
  166 #define MCLBYTES        (1 << MCLSHIFT) /* size of an mbuf cluster */
  167 
  168 #if PAGE_SIZE < 2048
  169 #define MJUMPAGESIZE    MCLBYTES
  170 #elif PAGE_SIZE <= 8192
  171 #define MJUMPAGESIZE    PAGE_SIZE
  172 #else
  173 #define MJUMPAGESIZE    (8 * 1024)
  174 #endif
  175 
  176 #define MJUM9BYTES      (9 * 1024)      /* jumbo cluster 9k */
  177 #define MJUM16BYTES     (16 * 1024)     /* jumbo cluster 16k */
  178 
  179 /*
  180  * Some macros for units conversion
  181  */
  182 
  183 /* clicks to bytes */
  184 #ifndef ctob
  185 #define ctob(x) ((x)<<PAGE_SHIFT)
  186 #endif
  187 
  188 /* bytes to clicks */
  189 #ifndef btoc
  190 #define btoc(x) (((vm_offset_t)(x)+PAGE_MASK)>>PAGE_SHIFT)
  191 #endif
  192 
  193 /*
  194  * btodb() is messy and perhaps slow because `bytes' may be an off_t.  We
  195  * want to shift an unsigned type to avoid sign extension and we don't
  196  * want to widen `bytes' unnecessarily.  Assume that the result fits in
  197  * a daddr_t.
  198  */
  199 #ifndef btodb
  200 #define btodb(bytes)                    /* calculates (bytes / DEV_BSIZE) */ \
  201         (sizeof (bytes) > sizeof(long) \
  202          ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
  203          : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))
  204 #endif
  205 
  206 #ifndef dbtob
  207 #define dbtob(db)                       /* calculates (db * DEV_BSIZE) */ \
  208         ((off_t)(db) << DEV_BSHIFT)
  209 #endif
  210 
  211 #define PRIMASK 0x0ff
  212 #define PCATCH  0x100           /* OR'd with pri for tsleep to check signals */
  213 #define PDROP   0x200   /* OR'd with pri to stop re-entry of interlock mutex */
  214 #define PBDRY   0x400   /* for PCATCH stop is done on the user boundary */
  215 
  216 #define NZERO   0               /* default "nice" */
  217 
  218 #define NBBY    8               /* number of bits in a byte */
  219 #define NBPW    sizeof(int)     /* number of bytes per word (integer) */
  220 
  221 #define CMASK   022             /* default file mask: S_IWGRP|S_IWOTH */
  222 
  223 #define NODEV   (dev_t)(-1)     /* non-existent device */
  224 
  225 /*
  226  * File system parameters and macros.
  227  *
  228  * MAXBSIZE -   Filesystems are made out of blocks of at most MAXBSIZE bytes
  229  *              per block.  MAXBSIZE may be made larger without effecting
  230  *              any existing filesystems as long as it does not exceed MAXPHYS,
  231  *              and may be made smaller at the risk of not being able to use
  232  *              filesystems which require a block size exceeding MAXBSIZE.
  233  *
  234  * BKVASIZE -   Nominal buffer space per buffer, in bytes.  BKVASIZE is the
  235  *              minimum KVM memory reservation the kernel is willing to make.
  236  *              Filesystems can of course request smaller chunks.  Actual 
  237  *              backing memory uses a chunk size of a page (PAGE_SIZE).
  238  *
  239  *              If you make BKVASIZE too small you risk seriously fragmenting
  240  *              the buffer KVM map which may slow things down a bit.  If you
  241  *              make it too big the kernel will not be able to optimally use 
  242  *              the KVM memory reserved for the buffer cache and will wind 
  243  *              up with too-few buffers.
  244  *
  245  *              The default is 16384, roughly 2x the block size used by a
  246  *              normal UFS filesystem.
  247  */
  248 #define MAXBSIZE        65536   /* must be power of 2 */
  249 #define BKVASIZE        16384   /* must be power of 2 */
  250 #define BKVAMASK        (BKVASIZE-1)
  251 
  252 /*
  253  * MAXPATHLEN defines the longest permissible path length after expanding
  254  * symbolic links. It is used to allocate a temporary buffer from the buffer
  255  * pool in which to do the name expansion, hence should be a power of two,
  256  * and must be less than or equal to MAXBSIZE.  MAXSYMLINKS defines the
  257  * maximum number of symbolic links that may be expanded in a path name.
  258  * It should be set high enough to allow all legitimate uses, but halt
  259  * infinite loops reasonably quickly.
  260  */
  261 #define MAXPATHLEN      PATH_MAX
  262 #define MAXSYMLINKS     32
  263 
  264 /* Bit map related macros. */
  265 #define setbit(a,i)     (((unsigned char *)(a))[(i)/NBBY] |= 1<<((i)%NBBY))
  266 #define clrbit(a,i)     (((unsigned char *)(a))[(i)/NBBY] &= ~(1<<((i)%NBBY)))
  267 #define isset(a,i)                                                      \
  268         (((const unsigned char *)(a))[(i)/NBBY] & (1<<((i)%NBBY)))
  269 #define isclr(a,i)                                                      \
  270         ((((const unsigned char *)(a))[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
  271 
  272 /* Macros for counting and rounding. */
  273 #ifndef howmany
  274 #define howmany(x, y)   (((x)+((y)-1))/(y))
  275 #endif
  276 #define nitems(x)       (sizeof((x)) / sizeof((x)[0]))
  277 #define rounddown(x, y) (((x)/(y))*(y))
  278 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))  /* to any y */
  279 #define roundup2(x, y)  (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
  280 #define powerof2(x)     ((((x)-1)&(x))==0)
  281 
  282 /* Macros for min/max. */
  283 #define MIN(a,b) (((a)<(b))?(a):(b))
  284 #define MAX(a,b) (((a)>(b))?(a):(b))
  285 
  286 #ifdef _KERNEL
  287 /*
  288  * Basic byte order function prototypes for non-inline functions.
  289  */
  290 #ifndef LOCORE
  291 #ifndef _BYTEORDER_PROTOTYPED
  292 #define _BYTEORDER_PROTOTYPED
  293 __BEGIN_DECLS
  294 __uint32_t       htonl(__uint32_t);
  295 __uint16_t       htons(__uint16_t);
  296 __uint32_t       ntohl(__uint32_t);
  297 __uint16_t       ntohs(__uint16_t);
  298 __END_DECLS
  299 #endif
  300 #endif
  301 
  302 #ifndef lint
  303 #ifndef _BYTEORDER_FUNC_DEFINED
  304 #define _BYTEORDER_FUNC_DEFINED
  305 #define htonl(x)        __htonl(x)
  306 #define htons(x)        __htons(x)
  307 #define ntohl(x)        __ntohl(x)
  308 #define ntohs(x)        __ntohs(x)
  309 #endif /* !_BYTEORDER_FUNC_DEFINED */
  310 #endif /* lint */
  311 #endif /* _KERNEL */
  312 
  313 /*
  314  * Scale factor for scaled integers used to count %cpu time and load avgs.
  315  *
  316  * The number of CPU `tick's that map to a unique `%age' can be expressed
  317  * by the formula (1 / (2 ^ (FSHIFT - 11))).  The maximum load average that
  318  * can be calculated (assuming 32 bits) can be closely approximated using
  319  * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
  320  *
  321  * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
  322  * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
  323  */
  324 #define FSHIFT  11              /* bits to right of fixed binary point */
  325 #define FSCALE  (1<<FSHIFT)
  326 
  327 #define dbtoc(db)                       /* calculates devblks to pages */ \
  328         ((db + (ctodb(1) - 1)) >> (PAGE_SHIFT - DEV_BSHIFT))
  329  
  330 #define ctodb(db)                       /* calculates pages to devblks */ \
  331         ((db) << (PAGE_SHIFT - DEV_BSHIFT))
  332 
  333 /*
  334  * Old spelling of __containerof().
  335  */
  336 #define member2struct(s, m, x)                                          \
  337         ((struct s *)(void *)((char *)(x) - offsetof(struct s, m)))
  338 
  339 /*
  340  * Access a variable length array that has been declared as a fixed
  341  * length array.
  342  */
  343 #define __PAST_END(array, offset) (((__typeof__(*(array)) *)(array))[offset])
  344 
  345 #endif  /* _SYS_PARAM_H_ */

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