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

     /*      $NetBSD: param.h,v 1.724 2022/12/21 18:03:48 pgoyette Exp $     */
     
     /*-
      * 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. 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
     */
    
    #ifndef _SYS_PARAM_H_
    #define _SYS_PARAM_H_
    
    #ifdef _KERNEL_OPT
    #include "opt_param.h"
    #endif
    
    /*
     * Historic BSD #defines -- probably will remain untouched for all time.
     */
    #define BSD     199506          /* System version (year & month). */
    #define BSD4_3  1
    #define BSD4_4  1
    
    /*
     *      #define __NetBSD_Version__ MMmmrrpp00
     *
     *      M = major version
     *      m = minor version; a minor number of 99 indicates current.
     *      r = 0 (*) or patchlevel in 9.99
     *      p = patchlevel
     *
     * When new releases are made, src/gnu/usr.bin/groff/tmac/mdoc.local
     * needs to be updated and the changes sent back to the groff maintainers.
     *
     * (*)  Up to 2.0I "release" used to be "",A-Z,Z[A-Z] but numeric
     *              e.g. NetBSD-1.2D  = 102040000 ('D' == 4)
     *      NetBSD-2.0H     (200080000) was changed on 20041001 to:
     *      2.99.9          (299000900)
     */
    
    #define __NetBSD_Version__      1099000200      /* NetBSD 10.99.2 */
    
    #define __NetBSD_Prereq__(M,m,p) (((((M) * 100000000) + \
        (m) * 1000000) + (p) * 100) <= __NetBSD_Version__)
    
    /*
     * Historical NetBSD #define
     *
     * NetBSD 1.4 was the last release for which this value was incremented.
     * The value is now permanently fixed at 199905. It will never be
     * changed again.
     *
     * New code must use __NetBSD_Version__ instead, and should not even
     * count on NetBSD being defined.
     *
     */
    
    #define NetBSD  199905          /* NetBSD version (year & month). */
    
    /*
     * These macros determine if we are running in protected mode or not.
     *   _HARDKERNEL: code uses kernel namespace and runs in hw privileged mode
     *   _SOFTKERNEL: code uses kernel namespace but runs without hw privileges
     */
    #if defined(_KERNEL) && !defined(_RUMPKERNEL)
    #define _HARDKERNEL
    #endif
    #if defined(_KERNEL) && defined(_RUMPKERNEL)
    #define _SOFTKERNEL
    #endif
   
   #include <sys/null.h>
   
   #ifndef __ASSEMBLER__
   #include <sys/inttypes.h>
   #include <sys/types.h>
   
   /*
    * 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>)
    * MAXHOSTNAMELEN should be >= (_POSIX_HOST_NAME_MAX + 1) (see <limits.h>)
    * MAXLOGNAME should be >= UT_NAMESIZE (see <utmp.h>)
    */
   #include <sys/syslimits.h>
   
   #define MAXCOMLEN       16              /* max command name remembered */
   #define MAXINTERP       PATH_MAX        /* max interpreter file name length */
   /* DEPRECATED: use LOGIN_NAME_MAX instead. */
   #define MAXLOGNAME      (LOGIN_NAME_MAX - 1) /* max login name length */
   #define NCARGS          ARG_MAX         /* max bytes for an exec function */
   #define NGROUPS         NGROUPS_MAX     /* max number groups */
   #define NOGROUP         65535           /* marker for empty group set member */
   #define MAXHOSTNAMELEN  256             /* max hostname size */
   
   #ifndef NOFILE
   #define NOFILE          OPEN_MAX        /* max open files per process */
   #endif
   #ifndef MAXUPRC                         /* max simultaneous processes */
   #define MAXUPRC         CHILD_MAX       /* POSIX 1003.1-compliant default */
   #else
   #if (MAXUPRC - 0) < CHILD_MAX
   #error MAXUPRC less than CHILD_MAX.  See options(4) for details.
   #endif /* (MAXUPRC - 0) < CHILD_MAX */
   #endif /* !defined(MAXUPRC) */
   
   /* Macros for min/max. */
   #define MIN(a,b)        ((/*CONSTCOND*/(a)<(b))?(a):(b))
   #define MAX(a,b)        ((/*CONSTCOND*/(a)>(b))?(a):(b))
   
   /* Machine type dependent parameters. */
   #include <machine/param.h>
   #include <machine/limits.h>
   
   /*
    * Coherency unit: assumed cache line size.  See also MIN_LWP_ALIGNMENT.
    * The MD code depends on the current values of these constants. Don't
    * change them without coordinating.
    */
   #ifndef COHERENCY_UNIT
   #define COHERENCY_UNIT          64
   #endif
   #ifndef CACHE_LINE_SIZE
   #define CACHE_LINE_SIZE         64
   #endif
   
   /* 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 <uvm/uvm_param.h>
   #ifndef NPROC
   #define NPROC                   (20 + 16 * MAXUSERS)
   #endif
   #ifndef MAXFILES
   #define MAXFILES                (3 * (NPROC + MAXUSERS) + 80)
   #define MAXFILES_IMPLICIT
   #endif
   #ifndef NTEXT
   #define NTEXT                   (80 + NPROC / 8) /* actually the object cache */
   #endif
   #ifndef NVNODE
   #define NVNODE                  (NPROC + NTEXT + 100)
   #define NVNODE_IMPLICIT
   #endif
   #ifndef VNODE_KMEM_MAXPCT
   #define VNODE_KMEM_MAXPCT       60
   #endif
   #ifndef BUFCACHE_VA_MAXPCT
   #define BUFCACHE_VA_MAXPCT      20
   #endif
   #define VNODE_COST              2048            /* assumed space in bytes */
   #endif /* _KERNEL */
   
   /* Signals. */
   #include <sys/signal.h>
   
   #define DEV_BSHIFT      9                       /* log2(DEV_BSIZE) */
   #define DEV_BSIZE       (1 << DEV_BSHIFT)       /* 512 */
   
   #ifndef BLKDEV_IOSIZE
   #define BLKDEV_IOSIZE   2048
   #endif
   
   #ifndef MAXPHYS
   #define MAXPHYS         (64 * 1024)             /* max raw I/O transfer size */
   #endif
   
   /* pages ("clicks") to disk blocks */
   #define ctod(x)         ((x) << (PGSHIFT - DEV_BSHIFT))
   #define dtoc(x)         ((x) >> (PGSHIFT - DEV_BSHIFT))
   
   /* bytes to pages */
   #define ctob(x)         ((x) << PGSHIFT)
   #define btoc(x)         (((x) + PGOFSET) >> PGSHIFT)
   
   /* bytes to disk blocks */
   #define dbtob(x)        ((x) << DEV_BSHIFT)
   #define btodb(x)        ((x) >> DEV_BSHIFT)
   
   #ifndef MAXCPUS
   #define MAXCPUS                 32
   #endif
   #ifndef MAX_LWP_PER_PROC
   #define MAX_LWP_PER_PROC        8000
   #endif
   
   /*
    * Stack macros.  On most architectures, the stack grows down,
    * towards lower addresses; it is the rare architecture where
    * it grows up, towards higher addresses.
    *
    * STACK_GROW and STACK_SHRINK adjust a stack pointer by some
    * size, no questions asked.  STACK_ALIGN aligns a stack pointer.
    *
    * STACK_ALLOC returns a pointer to allocated stack space of
    * some size; given such a pointer and a size, STACK_MAX gives
    * the maximum (in the "maxsaddr" sense) stack address of the
    * allocated memory.
    */
   #if defined(_KERNEL) || defined(__EXPOSE_STACK)
   
   #ifndef STACK_ALIGNBYTES
   #define STACK_ALIGNBYTES        __ALIGNBYTES
   #endif
   
   #ifdef __MACHINE_STACK_GROWS_UP
   #define STACK_GROW(sp, _size)           (((char *)(void *)(sp)) + (_size))
   #define STACK_SHRINK(sp, _size)         (((char *)(void *)(sp)) - (_size))
   #define STACK_ALIGN(sp, bytes)  \
           ((char *)((((unsigned long)(sp)) + (bytes)) & ~(bytes)))
   #define STACK_ALLOC(sp, _size)          ((char *)(void *)(sp))
   #define STACK_MAX(p, _size)             (((char *)(void *)(p)) + (_size))
   #else
   #define STACK_GROW(sp, _size)           (((char *)(void *)(sp)) - (_size))
   #define STACK_SHRINK(sp, _size)         (((char *)(void *)(sp)) + (_size))
   #define STACK_ALIGN(sp, bytes)  \
           ((char *)(((unsigned long)(sp)) & ~(bytes)))
   #define STACK_ALLOC(sp, _size)          (((char *)(void *)(sp)) - (_size))
   #define STACK_MAX(p, _size)             ((char *)(void *)(p))
   #endif
   #define STACK_LEN_ALIGN(len, bytes)     (((len) + (bytes)) & ~(bytes))
   
   #endif /* defined(_KERNEL) || defined(__EXPOSE_STACK) */
   
   /*
    * Round p (pointer or byte index) up to a correctly-aligned value for all
    * data types (int, long, ...).   The result is uintptr_t and must be cast to
    * any desired pointer type.
    *
    * ALIGNED_POINTER is a boolean macro that checks whether an address
    * is valid to fetch data elements of type t from on this architecture
    * using ALIGNED_POINTER_LOAD.  This does not reflect the optimal
    * alignment, just the possibility (within reasonable limits).
    *
    *      uint32_t x;
    *      unsigned char *p = ...;
    *
    *      if (ALIGNED_POINTER(p, uint32_t)) {
    *              uint32_t t;
    *              ALIGNED_POINTER_LOAD(&t, p, uint32_t);
    *              x = t;
    *      } else {
    *              uint32_t t;
    *              memcpy(&t, p, sizeof(t));
    *              x = t;
    *      }
    *
    */
   #define ALIGNBYTES      __ALIGNBYTES
   #ifndef ALIGN
   #define ALIGN(p)                (((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES)
   #endif
   #ifndef ALIGNED_POINTER
   #define ALIGNED_POINTER(p,t)    ((((uintptr_t)(p)) & (__alignof(t) - 1)) == 0)
   #endif
   #ifndef ALIGNED_POINTER_LOAD
   #define ALIGNED_POINTER_LOAD(q,p,t)     (*(q) = *((const t *)(p)))
   #endif
   
   /*
    * Return if pointer p is accessible for type t. For primitive types
    * this means that the pointer itself can be dereferenced; for structures
    * and unions this means that any field can be dereferenced. On CPUs
    * that allow unaligned pointer access, we always return that the pointer
    * is accessible to prevent unnecessary copies, although this might not be
    * necessarily faster.
    */
   #ifdef __NO_STRICT_ALIGNMENT
   #define ACCESSIBLE_POINTER(p, t)        1
   #else
   #define ACCESSIBLE_POINTER(p, t)        ALIGNED_POINTER(p, t)
   #endif
   
   /*
    * Historic priority levels.  These are meaningless and remain only
    * for source compatibility.  Do not use in new code.
    */
   #define PSWP    0
   #define PVM     4
   #define PINOD   8
   #define PRIBIO  16
   #define PVFS    20
   #define PZERO   22
   #define PSOCK   24
   #define PWAIT   32
   #define PLOCK   36
   #define PPAUSE  40
   #define PUSER   50
   #define MAXPRI  127
   
   #define PCATCH          0x100   /* OR'd with pri for tsleep to check signals */
   #define PNORELOCK       0x200   /* OR'd with pri for tsleep to not relock */
   
   /*
    * New priority levels.
    */
   #define PRI_COUNT               224
   #define PRI_NONE                (-1)
   
   #define PRI_KERNEL_RT           192
   #define NPRI_KERNEL_RT          32
   #define MAXPRI_KERNEL_RT        (PRI_KERNEL_RT + NPRI_KERNEL_RT - 1)
   
   #define PRI_USER_RT             128
   #define NPRI_USER_RT            64
   #define MAXPRI_USER_RT          (PRI_USER_RT + NPRI_USER_RT - 1)
   
   #define PRI_KTHREAD             96
   #define NPRI_KTHREAD            32
   #define MAXPRI_KTHREAD          (PRI_KTHREAD + NPRI_KTHREAD - 1)
   
   #define PRI_KERNEL              64
   #define NPRI_KERNEL             32
   #define MAXPRI_KERNEL           (PRI_KERNEL + NPRI_KERNEL - 1)
   
   #define PRI_USER                0
   #define NPRI_USER               64
   #define MAXPRI_USER             (PRI_USER + NPRI_USER - 1)
   
   /* Priority range used by POSIX real-time features */
   #define SCHED_PRI_MIN           0
   #define SCHED_PRI_MAX           63
   
   /*
    * Kernel thread priorities.
    */
   #define PRI_SOFTSERIAL  MAXPRI_KERNEL_RT
   #define PRI_SOFTNET     (MAXPRI_KERNEL_RT - schedppq * 1)
   #define PRI_SOFTBIO     (MAXPRI_KERNEL_RT - schedppq * 2)
   #define PRI_SOFTCLOCK   (MAXPRI_KERNEL_RT - schedppq * 3)
   
   #define PRI_XCALL       MAXPRI_KTHREAD
   #define PRI_PGDAEMON    (MAXPRI_KTHREAD - schedppq * 1)
   #define PRI_VM          (MAXPRI_KTHREAD - schedppq * 2)
   #define PRI_IOFLUSH     (MAXPRI_KTHREAD - schedppq * 3)
   #define PRI_BIO         (MAXPRI_KTHREAD - schedppq * 4)
   
   #define PRI_IDLE        PRI_USER
   
   /*
    * Miscellaneous.
    */
   #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.
    *
    * 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 may make some file systems unmountable.
    */
   #ifndef MAXBSIZE                                /* XXX */
   #define MAXBSIZE        MAXPHYS
   #endif
   #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.
    *
    * MAXSYMLINKS should be >= _POSIX_SYMLOOP_MAX (see <limits.h>)
    */
   #define MAXPATHLEN      PATH_MAX
   #define MAXSYMLINKS     32
   
   /*
    * This is the maximum individual filename component length enforced by
    * namei. Filesystems cannot exceed this limit. The upper bound for that
    * limit is NAME_MAX. We don't bump it for now, for compatibility with
    * old binaries during the time where MAXNAMLEN was 511 and NAME_MAX was
    * 255
    */
   #define KERNEL_NAME_MAX 255
   
   /* 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 roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
   #define rounddown(x,y)  (((x)/(y))*(y))
   
   /*
    * Rounding to powers of two.  The naive definitions of roundup2 and
    * rounddown2,
    *
    *      #define roundup2(x,m)   (((x) + ((m) - 1)) & ~((m) - 1))
    *      #define rounddown2(x,m) ((x) & ~((m) - 1)),
    *
    * exhibit a quirk of integer arithmetic in C because the complement
    * happens in the type of m, not in the type of x.  So if unsigned int
    * is 32-bit, and m is an unsigned int while x is a uint64_t, then
    * roundup2 and rounddown2 would have the unintended effect of clearing
    * the upper 32 bits of the result(!).  These definitions avoid the
    * pitfalls of C arithmetic depending on the types of x and m, and
    * additionally avoid multiply evaluating their arguments.
    */
   #define roundup2(x,m)   ((((x) - 1) | ((m) - 1)) + 1)
   #define rounddown2(x,m) ((x) & ~((__typeof__(x))((m) - 1)))
   
   #define powerof2(x)     ((((x)-1)&(x))==0)
   
   /*
    * 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: NBPG <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
    * MAXALLOCSAVE must be a power of two.
    */
   #ifdef _LP64
   #define MINBUCKET       5               /* 5 => min allocation of 32 bytes */
   #else
   #define MINBUCKET       4               /* 4 => min allocation of 16 bytes */
   #endif
   #define MAXALLOCSAVE    (2 * NBPG)
   
   /*
    * 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)
   
   /*
    * The time for a process to be blocked before being very swappable.
    * This is a number of seconds which the system takes as being a non-trivial
    * amount of real time.  You probably shouldn't change this;
    * it is used in subtle ways (fractions and multiples of it are, that is, like
    * half of a ``long time'', almost a long time, etc.)
    * It is related to human patience and other factors which don't really
    * change over time.
    */
   #define        MAXSLP          20
   
   /*
    * Defaults for Unified Buffer Cache parameters.
    * These may be overridden in <machine/param.h>.
    */
   
   #ifndef UBC_WINSHIFT
   #define UBC_WINSHIFT    13
   #endif
   #ifndef UBC_NWINS
   #define UBC_NWINS       1024
   #endif
   
   #ifdef _KERNEL
   extern int hz;
   /*
    * macro to convert from milliseconds to hz without integer overflow
    * The 32 bit version uses only 32bit arithmetic; 0x20000 is safe for hz < 20000
    * the 64 bit version does the computation directly.
    */
   #ifndef mstohz
   # ifdef _LP64
   #  define mstohz(ms) ((unsigned int)((ms + 0ul) * hz / 1000ul))
   # else
   static __inline unsigned int
   mstohz(unsigned int ms)
   {
           return __predict_false(ms >= 0x20000u) ?
               (ms / 1000u) * hz : (ms * hz) / 1000u;
   }
   # endif
   #endif
   
   #ifndef hztoms
   # ifdef _LP64
   #  define hztoms(t) ((unsigned int)(((t) + 0ul) * 1000ul / hz))
   # else
   static __inline unsigned int
   hztoms(unsigned int t)
   {
           return __predict_false(t >= 0x20000u) ?
               (t / hz) * 1000u : (t * 1000u) / hz;
   }
   # endif
   #endif
   
   #define hz2bintime(t)   (ms2bintime(hztoms(t)))
   
   extern const int schedppq;
   extern size_t coherency_unit;
   
   #endif /* _KERNEL */
   
   /*
    * Minimum alignment of "struct lwp" needed by the architecture.  This
    * counts when packing a lock byte into a word alongside a pointer to an
    * LWP.  We need a minimum of 32, but go with the cache line size.
    */
   #ifndef MIN_LWP_ALIGNMENT
   # if COHERENCY_UNIT > 32
   #  define MIN_LWP_ALIGNMENT     COHERENCY_UNIT
   # else
   #  define MIN_LWP_ALIGNMENT     32
   # endif
   #endif
   #endif /* !__ASSEMBLER__ */
   
   #endif /* !_SYS_PARAM_H_ */

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