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.
     * 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: releng/11.2/sys/sys/param.h 334459 2018-06-01 00:22:49Z gjb $
     */
    
    #ifndef _SYS_PARAM_H_
    #define _SYS_PARAM_H_
    
    #include <sys/_null.h>
    
    #define BSD     199506          /* System version (year & month). */
    #define BSD4_3  1
    #define BSD4_4  1
    
    /*
     * __FreeBSD_version numbers are documented in the Porter's Handbook.
     * If you bump the version for any reason, you should update the documentation
     * there.
     * Currently this lives here in the doc/ repository:
     *
     *      head/en_US.ISO8859-1/books/porters-handbook/versions/chapter.xml
     *
     * scheme is:  <major><two digit minor>Rxx
     *              'R' is in the range 0 to 4 if this is a release branch or
     *              X.0-CURRENT before releng/X.0 is created, otherwise 'R' is
     *              in the range 5 to 9.
     */
    #undef __FreeBSD_version
    #define __FreeBSD_version 1102000       /* Master, propagated to newvers */
    
    /*
     * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
     * which by definition is always true on FreeBSD. This macro is also defined
     * on other systems that use the kernel of FreeBSD, such as GNU/kFreeBSD.
     *
     * It is tempting to use this macro in userland code when we want to enable
     * kernel-specific routines, and in fact it's fine to do this in code that
     * is part of FreeBSD itself.  However, be aware that as presence of this
     * macro is still not widespread (e.g. older FreeBSD versions, 3rd party
     * compilers, etc), it is STRONGLY DISCOURAGED to check for this macro in
     * external applications without also checking for __FreeBSD__ as an
     * alternative.
     */
    #undef __FreeBSD_kernel__
    #define __FreeBSD_kernel__
    
    #if defined(_KERNEL) || defined(IN_RTLD)
    #define P_OSREL_SIGWAIT                 700000
    #define P_OSREL_SIGSEGV                 700004
    #define P_OSREL_MAP_ANON                800104
    #define P_OSREL_MAP_FSTRICT             1100036
    #define P_OSREL_SHUTDOWN_ENOTCONN       1100077
    #define P_OSREL_MAP_GUARD               1200035
    #define P_OSREL_MAP_GUARD_11            1101501
    #define P_OSREL_WRFSBASE                1200041
    #define P_OSREL_WRFSBASE_11             1101503
    
    #define P_OSREL_MAJOR(x)                ((x) / 100000)
    #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>)
    */
   #include <sys/syslimits.h>
   
   #define MAXCOMLEN       19              /* max command name remembered */
   #define MAXINTERP       PATH_MAX        /* max interpreter file name length */
   #define MAXLOGNAME      33              /* max login name length (incl. NUL) */
   #define MAXUPRC         CHILD_MAX       /* max simultaneous processes */
   #define NCARGS          ARG_MAX         /* max bytes for an exec function */
   #define NGROUPS         (NGROUPS_MAX+1) /* 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 */
   #define SPECNAMELEN     63              /* max length of devicename */
   
   /* More types and definitions used throughout the kernel. */
   #ifdef _KERNEL
   #include <sys/cdefs.h>
   #include <sys/errno.h>
   #ifndef LOCORE
   #include <sys/time.h>
   #include <sys/priority.h>
   #endif
   
   #ifndef FALSE
   #define FALSE   0
   #endif
   #ifndef TRUE
   #define TRUE    1
   #endif
   #endif
   
   #ifndef _KERNEL
   /* Signals. */
   #include <sys/signal.h>
   #endif
   
   /* Machine type dependent parameters. */
   #include <machine/param.h>
   #ifndef _KERNEL
   #include <sys/limits.h>
   #endif
   
   #ifndef DEV_BSHIFT
   #define DEV_BSHIFT      9               /* log2(DEV_BSIZE) */
   #endif
   #define DEV_BSIZE       (1<<DEV_BSHIFT)
   
   #ifndef BLKDEV_IOSIZE
   #define BLKDEV_IOSIZE  PAGE_SIZE        /* default block device I/O size */
   #endif
   #ifndef DFLTPHYS
   #define DFLTPHYS        (64 * 1024)     /* default max raw I/O transfer size */
   #endif
   #ifndef MAXPHYS
   #define MAXPHYS         (128 * 1024)    /* max raw I/O transfer size */
   #endif
   #ifndef MAXDUMPPGS
   #define MAXDUMPPGS      (DFLTPHYS/PAGE_SIZE)
   #endif
   
   /*
    * Constants related to network buffer management.
    * MCLBYTES must be no larger than PAGE_SIZE.
    */
   #ifndef MSIZE
   #define MSIZE           256             /* size of an mbuf */
   #endif
   
   #ifndef MCLSHIFT
   #define MCLSHIFT        11              /* convert bytes to mbuf clusters */
   #endif  /* MCLSHIFT */
   
   #define MCLBYTES        (1 << MCLSHIFT) /* size of an mbuf cluster */
   
   #if PAGE_SIZE < 2048
   #define MJUMPAGESIZE    MCLBYTES
   #elif PAGE_SIZE <= 8192
   #define MJUMPAGESIZE    PAGE_SIZE
   #else
   #define MJUMPAGESIZE    (8 * 1024)
   #endif
   
   #define MJUM9BYTES      (9 * 1024)      /* jumbo cluster 9k */
   #define MJUM16BYTES     (16 * 1024)     /* jumbo cluster 16k */
   
   /*
    * Some macros for units conversion
    */
   
   /* clicks to bytes */
   #ifndef ctob
   #define ctob(x) ((x)<<PAGE_SHIFT)
   #endif
   
   /* bytes to clicks */
   #ifndef btoc
   #define btoc(x) (((vm_offset_t)(x)+PAGE_MASK)>>PAGE_SHIFT)
   #endif
   
   /*
    * btodb() is messy and perhaps slow because `bytes' may be an off_t.  We
    * want to shift an unsigned type to avoid sign extension and we don't
    * want to widen `bytes' unnecessarily.  Assume that the result fits in
    * a daddr_t.
    */
   #ifndef btodb
   #define btodb(bytes)                    /* calculates (bytes / DEV_BSIZE) */ \
           (sizeof (bytes) > sizeof(long) \
            ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
            : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))
   #endif
   
   #ifndef dbtob
   #define dbtob(db)                       /* calculates (db * DEV_BSIZE) */ \
           ((off_t)(db) << DEV_BSHIFT)
   #endif
   
   #define PRIMASK 0x0ff
   #define PCATCH  0x100           /* OR'd with pri for tsleep to check signals */
   #define PDROP   0x200   /* OR'd with pri to stop re-entry of interlock mutex */
   
   #define NZERO   0               /* default "nice" */
   
   #define NBBY    8               /* number of bits in a byte */
   #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 */
   
   /*
    * File system parameters and macros.
    *
    * MAXBSIZE -   Filesystems are made out of blocks of at most MAXBSIZE bytes
    *              per block.  MAXBSIZE may be made larger without effecting
    *              any existing filesystems as long as it does not exceed MAXPHYS,
    *              and may be made smaller at the risk of not being able to use
    *              filesystems which require a block size exceeding MAXBSIZE.
    *
    * MAXBCACHEBUF - Maximum size of a buffer in the buffer cache.  This must
    *              be >= MAXBSIZE and can be set differently for different
    *              architectures by defining it in <machine/param.h>.
    *              Making this larger allows NFS to do larger reads/writes.
    *
    * BKVASIZE -   Nominal buffer space per buffer, in bytes.  BKVASIZE is the
    *              minimum KVM memory reservation the kernel is willing to make.
    *              Filesystems can of course request smaller chunks.  Actual
    *              backing memory uses a chunk size of a page (PAGE_SIZE).
    *              The default value here can be overridden on a per-architecture
    *              basis by defining it in <machine/param.h>.
    *
    *              If you make BKVASIZE too small you risk seriously fragmenting
    *              the buffer KVM map which may slow things down a bit.  If you
    *              make it too big the kernel will not be able to optimally use
    *              the KVM memory reserved for the buffer cache and will wind
    *              up with too-few buffers.
    *
    *              The default is 16384, roughly 2x the block size used by a
    *              normal UFS filesystem.
    */
   #define MAXBSIZE        65536   /* must be power of 2 */
   #ifndef MAXBCACHEBUF
   #define MAXBCACHEBUF    MAXBSIZE /* must be a power of 2 >= MAXBSIZE */
   #endif
   #ifndef BKVASIZE
   #define BKVASIZE        16384   /* must be power of 2 */
   #endif
   #define BKVAMASK        (BKVASIZE-1)
   
   /*
    * 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)     (((unsigned char *)(a))[(i)/NBBY] |= 1<<((i)%NBBY))
   #define clrbit(a,i)     (((unsigned char *)(a))[(i)/NBBY] &= ~(1<<((i)%NBBY)))
   #define isset(a,i)                                                      \
           (((const unsigned char *)(a))[(i)/NBBY] & (1<<((i)%NBBY)))
   #define isclr(a,i)                                                      \
           ((((const unsigned char *)(a))[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
   
   /* Macros for counting and rounding. */
   #ifndef howmany
   #define howmany(x, y)   (((x)+((y)-1))/(y))
   #endif
   #define nitems(x)       (sizeof((x)) / sizeof((x)[0]))
   #define rounddown(x, y) (((x)/(y))*(y))
   #define rounddown2(x, y) ((x)&(~((y)-1)))          /* if y is power of two */
   #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. */
   #define MIN(a,b) (((a)<(b))?(a):(b))
   #define MAX(a,b) (((a)>(b))?(a):(b))
   
   #ifdef _KERNEL
   /*
    * Basic byte order function prototypes for non-inline functions.
    */
   #ifndef LOCORE
   #ifndef _BYTEORDER_PROTOTYPED
   #define _BYTEORDER_PROTOTYPED
   __BEGIN_DECLS
   __uint32_t       htonl(__uint32_t);
   __uint16_t       htons(__uint16_t);
   __uint32_t       ntohl(__uint32_t);
   __uint16_t       ntohs(__uint16_t);
   __END_DECLS
   #endif
   #endif
   
   #ifndef lint
   #ifndef _BYTEORDER_FUNC_DEFINED
   #define _BYTEORDER_FUNC_DEFINED
   #define htonl(x)        __htonl(x)
   #define htons(x)        __htons(x)
   #define ntohl(x)        __ntohl(x)
   #define ntohs(x)        __ntohs(x)
   #endif /* !_BYTEORDER_FUNC_DEFINED */
   #endif /* lint */
   #endif /* _KERNEL */
   
   /*
    * 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)
   
   #define dbtoc(db)                       /* calculates devblks to pages */ \
           ((db + (ctodb(1) - 1)) >> (PAGE_SHIFT - DEV_BSHIFT))
   
   #define ctodb(db)                       /* calculates pages to devblks */ \
           ((db) << (PAGE_SHIFT - DEV_BSHIFT))
   
   /*
    * Old spelling of __containerof().
    */
   #define member2struct(s, m, x)                                          \
           ((struct s *)(void *)((char *)(x) - offsetof(struct s, m)))
   
   /*
    * Access a variable length array that has been declared as a fixed
    * length array.
    */
   #define __PAST_END(array, offset) (((__typeof__(*(array)) *)(array))[offset])
   
   #endif  /* _SYS_PARAM_H_ */

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