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.
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14 * notice, this list of conditions and the following disclaimer.
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38 * @(#)param.h 8.3 (Berkeley) 4/4/95
45 #define BSD 199506 /* System version (year & month). */
50 * __FreeBSD_version numbers are documented in the Porter's Handbook.
51 * If you bump the version for any reason, you should update the documentation
53 * Currently this lives here:
55 * doc/en_US.ISO8859-1/books/porters-handbook/book.sgml
57 #undef __FreeBSD_version
58 #define __FreeBSD_version 500039 /* Master, propagated to newvers */
65 #include <sys/types.h>
69 * Machine-independent constants (some used in following include files).
70 * Redefined constants are from POSIX 1003.1 limits file.
72 * MAXCOMLEN should be >= sizeof(ac_comm) (see <acct.h>)
73 * MAXLOGNAME should be == UT_NAMESIZE+1 (see <utmp.h>)
75 #include <sys/syslimits.h>
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 15 /* max length of devicename */
88 /* More types and definitions used throughout the kernel. */
90 #include <sys/cdefs.h>
91 #include <sys/errno.h>
93 #include <sys/priority.h>
101 #include <sys/signal.h>
104 /* Machine type dependent parameters. */
105 #include <machine/param.h>
107 #include <machine/limits.h>
110 #ifndef _NO_NAMESPACE_POLLUTION
113 #define DEV_BSHIFT 9 /* log2(DEV_BSIZE) */
115 #define DEV_BSIZE (1<<DEV_BSHIFT)
117 #ifndef BLKDEV_IOSIZE
118 #define BLKDEV_IOSIZE PAGE_SIZE /* default block device I/O size */
121 #define DFLTPHYS (64 * 1024) /* default max raw I/O transfer size */
124 #define MAXPHYS (128 * 1024) /* max raw I/O transfer size */
127 #define MAXDUMPPGS (DFLTPHYS/PAGE_SIZE)
131 * Constants related to network buffer management.
132 * MCLBYTES must be no larger than PAGE_SIZE.
135 #define MSIZE 256 /* size of an mbuf */
139 #define MCLSHIFT 11 /* convert bytes to mbuf clusters */
140 #endif /* MCLSHIFT */
142 #define MCLBYTES (1 << MCLSHIFT) /* size of an mbuf cluster */
145 * Some macros for units conversion
148 /* clicks to bytes */
150 #define ctob(x) ((x)<<PAGE_SHIFT)
153 /* bytes to clicks */
155 #define btoc(x) (((vm_offset_t)(x)+PAGE_MASK)>>PAGE_SHIFT)
159 * btodb() is messy and perhaps slow because `bytes' may be an off_t. We
160 * want to shift an unsigned type to avoid sign extension and we don't
161 * want to widen `bytes' unnecessarily. Assume that the result fits in
165 #define btodb(bytes) /* calculates (bytes / DEV_BSIZE) */ \
166 (sizeof (bytes) > sizeof(long) \
167 ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
168 : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))
172 #define dbtob(db) /* calculates (db * DEV_BSIZE) */ \
173 ((off_t)(db) << DEV_BSHIFT)
176 #endif /* _NO_NAMESPACE_POLLUTION */
178 #define PRIMASK 0x0ff
179 #define PCATCH 0x100 /* OR'd with pri for tsleep to check signals */
180 #define PDROP 0x200 /* OR'd with pri to stop re-entry of interlock mutex */
182 #define NZERO 0 /* default "nice" */
184 #define NBPW sizeof(int) /* number of bytes per word (integer) */
186 #define CMASK 022 /* default file mask: S_IWGRP|S_IWOTH */
187 #define NODEV (dev_t)(-1) /* non-existent device */
189 #define NOUDEV (udev_t)(-1) /* non-existent device */
190 #define NOMAJ 256 /* non-existent device */
193 #define CBLOCK 128 /* Clist block size, must be a power of 2. */
194 #define CBQSIZE (CBLOCK/NBBY) /* Quote bytes/cblock - can do better. */
195 /* Data chars/clist. */
196 #define CBSIZE (CBLOCK - sizeof(struct cblock *) - CBQSIZE)
197 #define CROUND (CBLOCK - 1) /* Clist rounding. */
200 * File system parameters and macros.
202 * MAXBSIZE - Filesystems are made out of blocks of at most MAXBSIZE bytes
203 * per block. MAXBSIZE may be made larger without effecting
204 * any existing filesystems as long as it does not exceed MAXPHYS,
205 * and may be made smaller at the risk of not being able to use
206 * filesystems which require a block size exceeding MAXBSIZE.
208 * BKVASIZE - Nominal buffer space per buffer, in bytes. BKVASIZE is the
209 * minimum KVM memory reservation the kernel is willing to make.
210 * Filesystems can of course request smaller chunks. Actual
211 * backing memory uses a chunk size of a page (PAGE_SIZE).
213 * If you make BKVASIZE too small you risk seriously fragmenting
214 * the buffer KVM map which may slow things down a bit. If you
215 * make it too big the kernel will not be able to optimally use
216 * the KVM memory reserved for the buffer cache and will wind
217 * up with too-few buffers.
219 * The default is 16384, roughly 2x the block size used by a
220 * normal UFS filesystem.
222 #define MAXBSIZE 65536 /* must be power of 2 */
223 #define BKVASIZE 16384 /* must be power of 2 */
224 #define BKVAMASK (BKVASIZE-1)
227 * MAXPATHLEN defines the longest permissible path length after expanding
228 * symbolic links. It is used to allocate a temporary buffer from the buffer
229 * pool in which to do the name expansion, hence should be a power of two,
230 * and must be less than or equal to MAXBSIZE. MAXSYMLINKS defines the
231 * maximum number of symbolic links that may be expanded in a path name.
232 * It should be set high enough to allow all legitimate uses, but halt
233 * infinite loops reasonably quickly.
235 #define MAXPATHLEN PATH_MAX
236 #define MAXSYMLINKS 32
238 /* Bit map related macros. */
239 #define setbit(a,i) ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
240 #define clrbit(a,i) ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
241 #define isset(a,i) ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
242 #define isclr(a,i) (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
244 /* Macros for counting and rounding. */
246 #define howmany(x, y) (((x)+((y)-1))/(y))
248 #define rounddown(x, y) (((x)/(y))*(y))
249 #define roundup(x, y) ((((x)+((y)-1))/(y))*(y)) /* to any y */
250 #define roundup2(x, y) (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
251 #define powerof2(x) ((((x)-1)&(x))==0)
253 /* Macros for min/max. */
255 #define MIN(a,b) (((a)<(b))?(a):(b))
256 #define MAX(a,b) (((a)>(b))?(a):(b))
261 * Basic byte order function prototypes for non-inline functions.
263 #ifndef _BYTEORDER_PROTOTYPED
264 #define _BYTEORDER_PROTOTYPED
266 __uint32_t htonl(__uint32_t);
267 __uint16_t htons(__uint16_t);
268 __uint32_t ntohl(__uint32_t);
269 __uint16_t ntohs(__uint16_t);
274 #ifndef _BYTEORDER_FUNC_DEFINED
275 #define _BYTEORDER_FUNC_DEFINED
276 #define htonl(x) __htonl(x)
277 #define htons(x) __htons(x)
278 #define ntohl(x) __ntohl(x)
279 #define ntohs(x) __ntohs(x)
280 #endif /* !_BYTEORDER_FUNC_DEFINED */
285 * Constants for setting the parameters of the kernel memory allocator.
287 * 2 ** MINBUCKET is the smallest unit of memory that will be
288 * allocated. It must be at least large enough to hold a pointer.
290 * Units of memory less or equal to MAXALLOCSAVE will permanently
291 * allocate physical memory; requests for these size pieces of
292 * memory are quite fast. Allocations greater than MAXALLOCSAVE must
293 * always allocate and free physical memory; requests for these
294 * size allocations should be done infrequently as they will be slow.
296 * Constraints: PAGE_SIZE <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
297 * MAXALLOCSIZE must be a power of two.
299 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
300 #define MINBUCKET 5 /* 5 => min allocation of 32 bytes */
302 #define MINBUCKET 4 /* 4 => min allocation of 16 bytes */
304 #define MAXALLOCSAVE (2 * PAGE_SIZE)
307 * Scale factor for scaled integers used to count %cpu time and load avgs.
309 * The number of CPU `tick's that map to a unique `%age' can be expressed
310 * by the formula (1 / (2 ^ (FSHIFT - 11))). The maximum load average that
311 * can be calculated (assuming 32 bits) can be closely approximated using
312 * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
314 * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
315 * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
317 #define FSHIFT 11 /* bits to right of fixed binary point */
318 #define FSCALE (1<<FSHIFT)
320 #define dbtoc(db) /* calculates devblks to pages */ \
321 ((db + (ctodb(1) - 1)) >> (PAGE_SHIFT - DEV_BSHIFT))
323 #define ctodb(db) /* calculates pages to devblks */ \
324 ((db) << (PAGE_SHIFT - DEV_BSHIFT))
326 #endif /* _SYS_PARAM_H_ */