2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
3 * Copyright (c) 2001-2004 Mark R. V. Murray
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
36 #include <sys/kernel.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
42 #include <machine/bus.h>
44 /* For use with destroy_dev(9). */
45 static struct cdev *null_dev;
46 static struct cdev *zero_dev;
48 static d_write_t null_write;
49 static d_ioctl_t null_ioctl;
50 static d_read_t zero_read;
55 static struct cdevsw null_cdevsw = {
56 .d_version = D_VERSION,
57 .d_read = (d_read_t *)nullop,
58 .d_write = null_write,
59 .d_ioctl = null_ioctl,
63 static struct cdevsw zero_cdevsw = {
64 .d_version = D_VERSION,
66 .d_write = null_write,
68 .d_flags = D_MMAP_ANON,
75 null_write(struct cdev *dev __unused, struct uio *uio, int flags __unused)
84 null_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data __unused,
85 int flags __unused, struct thread *td)
89 if (cmd != DIOCSKERNELDUMP)
91 error = priv_check(td, PRIV_SETDUMPER);
94 return (set_dumper(NULL));
99 zero_read(struct cdev *dev __unused, struct uio *uio, int flags __unused)
103 while (uio->uio_resid > 0 && error == 0)
104 error = uiomove(zbuf, MIN(uio->uio_resid, PAGE_SIZE), uio);
111 null_modevent(module_t mod __unused, int type, void *data __unused)
116 printf("null: <null device, zero device>\n");
117 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO);
118 null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
119 GID_WHEEL, 0666, "null");
120 zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
121 GID_WHEEL, 0666, "zero");
125 destroy_dev(null_dev);
126 destroy_dev(zero_dev);
140 DEV_MODULE(null, null_modevent, NULL);
141 MODULE_VERSION(null, 1);