New machine independant /dev/null and /dev/zero driver. This device is
severely stripped down compared with its predecessor, and is measurably a _lot_ faster. Many thanks to Jeroen van Gelderen for lots of good ideas. There is still a problem with this; it is written as a mudule, and as such is theoretically unloadable. However, there is no refcounting done as I would prefer to do that a'la device_busy(9), rather than some "home-rolled" scheme. The point is pretty moot, as /dev/null is effectively compulsory. Reviewed by: dfr
This commit is contained in:
markm
parent
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137
sys/dev/null/null.c
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137
sys/dev/null/null.c
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/*-
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* Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/uio.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/bus.h>
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#include <machine/bus.h>
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#include <machine/resource.h>
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#include <sys/rman.h>
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/* For use with destroy_dev(9). */
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static dev_t null_dev;
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static dev_t zero_dev;
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static d_read_t nullwrite;
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static d_read_t zeroread;
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#define CDEV_MAJOR 2
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#define NULL_MINOR 2
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#define ZERO_MINOR 12
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static struct cdevsw null_cdevsw = {
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/* open */ (d_open_t *)nullop,
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/* close */ (d_close_t *)nullop,
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/* read */ (d_read_t *)nullop,
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/* write */ nullwrite,
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/* ioctl */ noioctl,
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/* poll */ nopoll,
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/* mmap */ nommap,
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/* strategy */ nostrategy,
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/* name */ "null",
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/* maj */ CDEV_MAJOR,
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/* dump */ nodump,
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/* psize */ nopsize,
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/* flags */ 0,
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/* bmaj */ -1
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};
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static struct cdevsw zero_cdevsw = {
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/* open */ (d_open_t *)nullop,
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/* close */ (d_close_t *)nullop,
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/* read */ zeroread,
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/* write */ nullwrite,
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/* ioctl */ noioctl,
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/* poll */ nopoll,
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/* mmap */ nommap,
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/* strategy */ nostrategy,
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/* name */ "zero",
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/* maj */ CDEV_MAJOR,
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/* dump */ nodump,
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/* psize */ nopsize,
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/* flags */ D_MMAP_ANON,
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/* bmaj */ -1
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};
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static void *zbuf;
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static int
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nullwrite(dev_t dev, struct uio *uio, int flag)
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{
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uio->uio_resid = 0;
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return 0;
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}
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static int
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zeroread(dev_t dev, struct uio *uio, int flag)
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{
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u_int c;
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int error = 0;
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while (uio->uio_resid > 0 && error == 0) {
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c = min(uio->uio_resid, PAGE_SIZE);
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error = uiomove(zbuf, c, uio);
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}
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return error;
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}
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static int
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null_modevent(module_t mod, int type, void *data)
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{
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switch(type) {
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case MOD_LOAD:
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if (bootverbose)
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printf("nulldev: <null device, zero device>\n");
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zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
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bzero(zbuf, PAGE_SIZE);
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zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "zero");
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null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "null");
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return 0;
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case MOD_UNLOAD:
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destroy_dev(null_dev);
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destroy_dev(zero_dev);
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free(zbuf, M_TEMP);
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return 0;
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case MOD_SHUTDOWN:
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return 0;
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default:
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return EOPNOTSUPP;
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}
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}
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DEV_MODULE(nulldev, null_modevent, NULL);
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137
sys/dev/nulldev/nulldev.c
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137
sys/dev/nulldev/nulldev.c
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@ -0,0 +1,137 @@
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/*-
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* Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer
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* in this position and unchanged.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/uio.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/bus.h>
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#include <machine/bus.h>
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#include <machine/resource.h>
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#include <sys/rman.h>
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/* For use with destroy_dev(9). */
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static dev_t null_dev;
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static dev_t zero_dev;
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static d_read_t nullwrite;
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static d_read_t zeroread;
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#define CDEV_MAJOR 2
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#define NULL_MINOR 2
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#define ZERO_MINOR 12
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static struct cdevsw null_cdevsw = {
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/* open */ (d_open_t *)nullop,
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/* close */ (d_close_t *)nullop,
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/* read */ (d_read_t *)nullop,
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/* write */ nullwrite,
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/* ioctl */ noioctl,
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/* poll */ nopoll,
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/* mmap */ nommap,
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/* strategy */ nostrategy,
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/* name */ "null",
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/* maj */ CDEV_MAJOR,
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/* dump */ nodump,
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/* psize */ nopsize,
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/* flags */ 0,
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/* bmaj */ -1
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};
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static struct cdevsw zero_cdevsw = {
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/* open */ (d_open_t *)nullop,
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/* close */ (d_close_t *)nullop,
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/* read */ zeroread,
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/* write */ nullwrite,
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/* ioctl */ noioctl,
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/* poll */ nopoll,
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/* mmap */ nommap,
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/* strategy */ nostrategy,
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/* name */ "zero",
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/* maj */ CDEV_MAJOR,
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/* dump */ nodump,
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/* psize */ nopsize,
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/* flags */ D_MMAP_ANON,
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/* bmaj */ -1
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};
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static void *zbuf;
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static int
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nullwrite(dev_t dev, struct uio *uio, int flag)
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{
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uio->uio_resid = 0;
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return 0;
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}
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static int
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zeroread(dev_t dev, struct uio *uio, int flag)
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{
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u_int c;
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int error = 0;
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while (uio->uio_resid > 0 && error == 0) {
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c = min(uio->uio_resid, PAGE_SIZE);
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error = uiomove(zbuf, c, uio);
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}
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return error;
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}
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static int
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null_modevent(module_t mod, int type, void *data)
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{
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switch(type) {
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case MOD_LOAD:
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if (bootverbose)
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printf("nulldev: <null device, zero device>\n");
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zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
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bzero(zbuf, PAGE_SIZE);
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zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "zero");
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null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT,
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GID_WHEEL, 0666, "null");
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return 0;
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case MOD_UNLOAD:
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destroy_dev(null_dev);
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destroy_dev(zero_dev);
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free(zbuf, M_TEMP);
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return 0;
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case MOD_SHUTDOWN:
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return 0;
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default:
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return EOPNOTSUPP;
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}
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}
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DEV_MODULE(nulldev, null_modevent, NULL);
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