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38 * @(#)param.h 8.3 (Berkeley) 4/4/95
39 * $FreeBSD: src/sys/sys/param.h,v 1.61.2.38 2003/05/22 17:12:01 fjoe Exp $
40 * $DragonFly: src/sys/sys/param.h,v 1.5 2003/08/01 17:46:23 dillon Exp $
46 #define BSD 199506 /* System version (year & month). */
51 * __FreeBSD_version numbers are documented in the Porter's Handbook.
52 * If you bump the version for any reason, you should update the documentation
54 * Currently this lives here:
55 * doc/en_US.ISO8859-1/books/porters-handbook/book.sgml
57 #undef __FreeBSD_version
58 #define __FreeBSD_version 480101 /* 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 16 /* 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 */
87 /* More types and definitions used throughout the kernel. */
89 #include <sys/cdefs.h>
90 #include <sys/errno.h>
99 #include <sys/signal.h>
102 /* Machine type dependent parameters. */
103 #include <machine/param.h>
105 #include <machine/limits.h>
109 * Priorities. Note that with 32 run queues, differences less than 4 are
113 #define MAXPRI 127 /* Priorities range from 0 through MAXPRI. */
115 #define PCATCH 0x0100 /* OR'd with pri for tsleep to check signals */
116 #define PUSRFLAG1 0x0200 /* Subsystem specific flag */
118 #define NZERO 0 /* default "nice" */
120 #define NBPW sizeof(int) /* number of bytes per word (integer) */
122 #define CMASK 022 /* default file mask: S_IWGRP|S_IWOTH */
124 #define NODEV (dev_t)(-1) /* non-existent device */
125 #define NOUDEV (udev_t)(-1) /* non-existent device */
126 #define NOMAJ 256 /* non-existent device */
128 #define NODEV (dev_t)(-1) /* non-existent device */
132 * Clustering of hardware pages on machines with ridiculously small
133 * page sizes is done here. The paging subsystem deals with units of
134 * CLSIZE pte's describing PAGE_SIZE (from machine/machparam.h) pages each.
137 #define CLBYTES (CLSIZE*PAGE_SIZE)
140 #define CBLOCK 128 /* Clist block size, must be a power of 2. */
141 #define CBQSIZE (CBLOCK/NBBY) /* Quote bytes/cblock - can do better. */
142 /* Data chars/clist. */
143 #define CBSIZE (CBLOCK - sizeof(struct cblock *) - CBQSIZE)
144 #define CROUND (CBLOCK - 1) /* Clist rounding. */
147 * File system parameters and macros.
149 * MAXBSIZE - Filesystems are made out of blocks of at most MAXBSIZE bytes
150 * per block. MAXBSIZE may be made larger without effecting
151 * any existing filesystems as long as it does not exceed MAXPHYS,
152 * and may be made smaller at the risk of not being able to use
153 * filesystems which require a block size exceeding MAXBSIZE.
155 * BKVASIZE - Nominal buffer space per buffer, in bytes. BKVASIZE is the
156 * minimum KVM memory reservation the kernel is willing to make.
157 * Filesystems can of course request smaller chunks. Actual
158 * backing memory uses a chunk size of a page (PAGE_SIZE).
160 * If you make BKVASIZE too small you risk seriously fragmenting
161 * the buffer KVM map which may slow things down a bit. If you
162 * make it too big the kernel will not be able to optimally use
163 * the KVM memory reserved for the buffer cache and will wind
164 * up with too-few buffers.
166 * The default is 16384, roughly 2x the block size used by a
167 * normal UFS filesystem.
169 #define MAXBSIZE 65536 /* must be power of 2 */
170 #define BKVASIZE 16384 /* must be power of 2 */
171 #define BKVAMASK (BKVASIZE-1)
175 * MAXPATHLEN defines the longest permissible path length after expanding
176 * symbolic links. It is used to allocate a temporary buffer from the buffer
177 * pool in which to do the name expansion, hence should be a power of two,
178 * and must be less than or equal to MAXBSIZE. MAXSYMLINKS defines the
179 * maximum number of symbolic links that may be expanded in a path name.
180 * It should be set high enough to allow all legitimate uses, but halt
181 * infinite loops reasonably quickly.
183 #define MAXPATHLEN PATH_MAX
184 #define MAXSYMLINKS 32
186 /* Bit map related macros. */
187 #define setbit(a,i) ((a)[(i)/NBBY] |= 1<<((i)%NBBY))
188 #define clrbit(a,i) ((a)[(i)/NBBY] &= ~(1<<((i)%NBBY)))
189 #define isset(a,i) ((a)[(i)/NBBY] & (1<<((i)%NBBY)))
190 #define isclr(a,i) (((a)[(i)/NBBY] & (1<<((i)%NBBY))) == 0)
192 /* Macros for counting and rounding. */
194 #define howmany(x, y) (((x)+((y)-1))/(y))
196 #define rounddown(x, y) (((x)/(y))*(y))
197 #define roundup(x, y) ((((x)+((y)-1))/(y))*(y)) /* to any y */
198 #define roundup2(x, y) (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
199 #define powerof2(x) ((((x)-1)&(x))==0)
201 /* Macros for min/max. */
202 #define MIN(a,b) (((a)<(b))?(a):(b))
203 #define MAX(a,b) (((a)>(b))?(a):(b))
206 * Constants for setting the parameters of the kernel memory allocator.
208 * 2 ** MINBUCKET is the smallest unit of memory that will be
209 * allocated. It must be at least large enough to hold a pointer.
211 * Units of memory less or equal to MAXALLOCSAVE will permanently
212 * allocate physical memory; requests for these size pieces of
213 * memory are quite fast. Allocations greater than MAXALLOCSAVE must
214 * always allocate and free physical memory; requests for these
215 * size allocations should be done infrequently as they will be slow.
217 * Constraints: PAGE_SIZE <= MAXALLOCSAVE <= 2 ** (MINBUCKET + 14), and
218 * MAXALLOCSIZE must be a power of two.
220 #if defined(__alpha__)
221 #define MINBUCKET 5 /* 5 => min allocation of 32 bytes */
223 #define MINBUCKET 4 /* 4 => min allocation of 16 bytes */
225 #define MAXALLOCSAVE (2 * PAGE_SIZE)
228 * Scale factor for scaled integers used to count %cpu time and load avgs.
230 * The number of CPU `tick's that map to a unique `%age' can be expressed
231 * by the formula (1 / (2 ^ (FSHIFT - 11))). The maximum load average that
232 * can be calculated (assuming 32 bits) can be closely approximated using
233 * the formula (2 ^ (2 * (16 - FSHIFT))) for (FSHIFT < 15).
235 * For the scheduler to maintain a 1:1 mapping of CPU `tick' to `%age',
236 * FSHIFT must be at least 11; this gives us a maximum load avg of ~1024.
238 #define FSHIFT 11 /* bits to right of fixed binary point */
239 #define FSCALE (1<<FSHIFT)
241 #define dbtoc(db) /* calculates devblks to pages */ \
242 ((db + (ctodb(1) - 1)) >> (PAGE_SHIFT - DEV_BSHIFT))
244 #define ctodb(db) /* calculates pages to devblks */ \
245 ((db) << (PAGE_SHIFT - DEV_BSHIFT))
249 * Make this available for most of the kernel. There were too many
250 * things that included sys/systm.h just for panic().
253 void panic __P((const char *, ...)) __dead2 __printflike(1, 2);
256 #endif /* _SYS_PARAM_H_ */