No empty .Rs/.Re

[netbsd-mini2440.git] / sys / kern / kern_subr.c

/*      $NetBSD: kern_subr.c,v 1.202 2009/11/04 16:54:00 pooka Exp $    */

/*-
 * Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center, and by Luke Mewburn.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1982, 1986, 1991, 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.
 *
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Lawrence Berkeley Laboratory.
 *
 * 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.
 *
 *      @(#)kern_subr.c 8.4 (Berkeley) 2/14/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.202 2009/11/04 16:54:00 pooka Exp $");

#include "opt_ddb.h"
#include "opt_md.h"
#include "opt_syscall_debug.h"
#include "opt_ktrace.h"
#include "opt_ptrace.h"
#include "opt_powerhook.h"
#include "opt_tftproot.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/device.h>
#include <sys/reboot.h>
#include <sys/conf.h>
#include <sys/disk.h>
#include <sys/disklabel.h>
#include <sys/queue.h>
#include <sys/ktrace.h>
#include <sys/ptrace.h>
#include <sys/fcntl.h>
#include <sys/kauth.h>
#include <sys/vnode.h>
#include <sys/syscallvar.h>
#include <sys/xcall.h>
#include <sys/module.h>

#include <uvm/uvm_extern.h>

#include <dev/cons.h>

#include <net/if.h>

/* XXX these should eventually move to subr_autoconf.c */
static device_t finddevice(const char *);
static device_t getdisk(char *, int, int, dev_t *, int);
static device_t parsedisk(char *, int, int, dev_t *);
static const char *getwedgename(const char *, int);

/*
 * A generic linear hook.
 */
struct hook_desc {
        LIST_ENTRY(hook_desc) hk_list;
        void    (*hk_fn)(void *);
        void    *hk_arg;
};
typedef LIST_HEAD(, hook_desc) hook_list_t;

#ifdef TFTPROOT
int tftproot_dhcpboot(device_t);
#endif

dev_t   dumpcdev;       /* for savecore */

static void *
hook_establish(hook_list_t *list, void (*fn)(void *), void *arg)
{
        struct hook_desc *hd;

        hd = malloc(sizeof(*hd), M_DEVBUF, M_NOWAIT);
        if (hd == NULL)
                return (NULL);

        hd->hk_fn = fn;
        hd->hk_arg = arg;
        LIST_INSERT_HEAD(list, hd, hk_list);

        return (hd);
}

static void
hook_disestablish(hook_list_t *list, void *vhook)
{
#ifdef DIAGNOSTIC
        struct hook_desc *hd;

        LIST_FOREACH(hd, list, hk_list) {
                if (hd == vhook)
                        break;
        }

        if (hd == NULL)
                panic("hook_disestablish: hook %p not established", vhook);
#endif
        LIST_REMOVE((struct hook_desc *)vhook, hk_list);
        free(vhook, M_DEVBUF);
}

static void
hook_destroy(hook_list_t *list)
{
        struct hook_desc *hd;

        while ((hd = LIST_FIRST(list)) != NULL) {
                LIST_REMOVE(hd, hk_list);
                free(hd, M_DEVBUF);
        }
}

static void
hook_proc_run(hook_list_t *list, struct proc *p)
{
        struct hook_desc *hd;

        LIST_FOREACH(hd, list, hk_list)
                ((void (*)(struct proc *, void *))*hd->hk_fn)(p, hd->hk_arg);
}

/*
 * "Shutdown hook" types, functions, and variables.
 *
 * Should be invoked immediately before the
 * system is halted or rebooted, i.e. after file systems unmounted,
 * after crash dump done, etc.
 *
 * Each shutdown hook is removed from the list before it's run, so that
 * it won't be run again.
 */

static hook_list_t shutdownhook_list;

void *
shutdownhook_establish(void (*fn)(void *), void *arg)
{
        return hook_establish(&shutdownhook_list, fn, arg);
}

void
shutdownhook_disestablish(void *vhook)
{
        hook_disestablish(&shutdownhook_list, vhook);
}

/*
 * Run shutdown hooks.  Should be invoked immediately before the
 * system is halted or rebooted, i.e. after file systems unmounted,
 * after crash dump done, etc.
 *
 * Each shutdown hook is removed from the list before it's run, so that
 * it won't be run again.
 */
void
doshutdownhooks(void)
{
        struct hook_desc *dp;

        while ((dp = LIST_FIRST(&shutdownhook_list)) != NULL) {
                LIST_REMOVE(dp, hk_list);
                (*dp->hk_fn)(dp->hk_arg);
#if 0
                /*
                 * Don't bother freeing the hook structure,, since we may
                 * be rebooting because of a memory corruption problem,
                 * and this might only make things worse.  It doesn't
                 * matter, anyway, since the system is just about to
                 * reboot.
                 */
                free(dp, M_DEVBUF);
#endif
        }
}

/*
 * "Mountroot hook" types, functions, and variables.
 */

static hook_list_t mountroothook_list;

void *
mountroothook_establish(void (*fn)(device_t), device_t dev)
{
        return hook_establish(&mountroothook_list, (void (*)(void *))fn, dev);
}

void
mountroothook_disestablish(void *vhook)
{
        hook_disestablish(&mountroothook_list, vhook);
}

void
mountroothook_destroy(void)
{
        hook_destroy(&mountroothook_list);
}

void
domountroothook(void)
{
        struct hook_desc *hd;

        LIST_FOREACH(hd, &mountroothook_list, hk_list) {
                if (hd->hk_arg == (void *)root_device) {
                        (*hd->hk_fn)(hd->hk_arg);
                        return;
                }
        }
}

static hook_list_t exechook_list;

void *
exechook_establish(void (*fn)(struct proc *, void *), void *arg)
{
        return hook_establish(&exechook_list, (void (*)(void *))fn, arg);
}

void
exechook_disestablish(void *vhook)
{
        hook_disestablish(&exechook_list, vhook);
}

/*
 * Run exec hooks.
 */
void
doexechooks(struct proc *p)
{
        hook_proc_run(&exechook_list, p);
}

static hook_list_t exithook_list;
extern krwlock_t exec_lock;

void *
exithook_establish(void (*fn)(struct proc *, void *), void *arg)
{
        void *rv;

        rw_enter(&exec_lock, RW_WRITER);
        rv = hook_establish(&exithook_list, (void (*)(void *))fn, arg);
        rw_exit(&exec_lock);
        return rv;
}

void
exithook_disestablish(void *vhook)
{

        rw_enter(&exec_lock, RW_WRITER);
        hook_disestablish(&exithook_list, vhook);
        rw_exit(&exec_lock);
}

/*
 * Run exit hooks.
 */
void
doexithooks(struct proc *p)
{
        hook_proc_run(&exithook_list, p);
}

static hook_list_t forkhook_list;

void *
forkhook_establish(void (*fn)(struct proc *, struct proc *))
{
        return hook_establish(&forkhook_list, (void (*)(void *))fn, NULL);
}

void
forkhook_disestablish(void *vhook)
{
        hook_disestablish(&forkhook_list, vhook);
}

/*
 * Run fork hooks.
 */
void
doforkhooks(struct proc *p2, struct proc *p1)
{
        struct hook_desc *hd;

        LIST_FOREACH(hd, &forkhook_list, hk_list) {
                ((void (*)(struct proc *, struct proc *))*hd->hk_fn)
                    (p2, p1);
        }
}

/*
 * "Power hook" types, functions, and variables.
 * The list of power hooks is kept ordered with the last registered hook
 * first.
 * When running the hooks on power down the hooks are called in reverse
 * registration order, when powering up in registration order.
 */
struct powerhook_desc {
        CIRCLEQ_ENTRY(powerhook_desc) sfd_list;
        void    (*sfd_fn)(int, void *);
        void    *sfd_arg;
        char    sfd_name[16];
};

static CIRCLEQ_HEAD(, powerhook_desc) powerhook_list =
    CIRCLEQ_HEAD_INITIALIZER(powerhook_list);

void *
powerhook_establish(const char *name, void (*fn)(int, void *), void *arg)
{
        struct powerhook_desc *ndp;

        ndp = (struct powerhook_desc *)
            malloc(sizeof(*ndp), M_DEVBUF, M_NOWAIT);
        if (ndp == NULL)
                return (NULL);

        ndp->sfd_fn = fn;
        ndp->sfd_arg = arg;
        strlcpy(ndp->sfd_name, name, sizeof(ndp->sfd_name));
        CIRCLEQ_INSERT_HEAD(&powerhook_list, ndp, sfd_list);

        aprint_error("%s: WARNING: powerhook_establish is deprecated\n", name);
        return (ndp);
}

void
powerhook_disestablish(void *vhook)
{
#ifdef DIAGNOSTIC
        struct powerhook_desc *dp;

        CIRCLEQ_FOREACH(dp, &powerhook_list, sfd_list)
                if (dp == vhook)
                        goto found;
        panic("powerhook_disestablish: hook %p not established", vhook);
 found:
#endif

        CIRCLEQ_REMOVE(&powerhook_list, (struct powerhook_desc *)vhook,
            sfd_list);
        free(vhook, M_DEVBUF);
}

/*
 * Run power hooks.
 */
void
dopowerhooks(int why)
{
        struct powerhook_desc *dp;

#ifdef POWERHOOK_DEBUG
        const char *why_name;
        static const char * pwr_names[] = {PWR_NAMES};
        why_name = why < __arraycount(pwr_names) ? pwr_names[why] : "???";
#endif

        if (why == PWR_RESUME || why == PWR_SOFTRESUME) {
                CIRCLEQ_FOREACH_REVERSE(dp, &powerhook_list, sfd_list) {
#ifdef POWERHOOK_DEBUG
                        printf("dopowerhooks %s: %s (%p)\n", why_name, dp->sfd_name, dp);
#endif
                        (*dp->sfd_fn)(why, dp->sfd_arg);
                }
        } else {
                CIRCLEQ_FOREACH(dp, &powerhook_list, sfd_list) {
#ifdef POWERHOOK_DEBUG
                        printf("dopowerhooks %s: %s (%p)\n", why_name, dp->sfd_name, dp);
#endif
                        (*dp->sfd_fn)(why, dp->sfd_arg);
                }
        }

#ifdef POWERHOOK_DEBUG
        printf("dopowerhooks: %s done\n", why_name);
#endif
}

static int
isswap(device_t dv)
{
        struct dkwedge_info wi;
        struct vnode *vn;
        int error;

        if (device_class(dv) != DV_DISK || !device_is_a(dv, "dk"))
                return 0;

        if ((vn = opendisk(dv)) == NULL)
                return 0;

        error = VOP_IOCTL(vn, DIOCGWEDGEINFO, &wi, FREAD, NOCRED);
        VOP_CLOSE(vn, FREAD, NOCRED);
        vput(vn);
        if (error) {
#ifdef DEBUG_WEDGE
                printf("%s: Get wedge info returned %d\n", device_xname(dv), error);
#endif
                return 0;
        }
        return strcmp(wi.dkw_ptype, DKW_PTYPE_SWAP) == 0;
}

/*
 * Determine the root device and, if instructed to, the root file system.
 */

#include "md.h"

#if NMD > 0
extern struct cfdriver md_cd;
#ifdef MEMORY_DISK_IS_ROOT
int md_is_root = 1;
#else
int md_is_root = 0;
#endif
#endif

/*
 * The device and wedge that we booted from.  If booted_wedge is NULL,
 * the we might consult booted_partition.
 */
device_t booted_device;
device_t booted_wedge;
int booted_partition;

/*
 * Use partition letters if it's a disk class but not a wedge.
 * XXX Check for wedge is kinda gross.
 */
#define DEV_USES_PARTITIONS(dv)                                         \
        (device_class((dv)) == DV_DISK &&                               \
         !device_is_a((dv), "dk"))

void
setroot(device_t bootdv, int bootpartition)
{
        device_t dv;
        deviter_t di;
        int len, majdev;
        dev_t nrootdev;
        dev_t ndumpdev = NODEV;
        char buf[128];
        const char *rootdevname;
        const char *dumpdevname;
        device_t rootdv = NULL;         /* XXX gcc -Wuninitialized */
        device_t dumpdv = NULL;
        struct ifnet *ifp;
        const char *deffsname;
        struct vfsops *vops;

#ifdef TFTPROOT
        if (tftproot_dhcpboot(bootdv) != 0)
                boothowto |= RB_ASKNAME;
#endif

#if NMD > 0
        if (md_is_root) {
                /*
                 * XXX there should be "root on md0" in the config file,
                 * but it isn't always
                 */
                bootdv = md_cd.cd_devs[0];
                bootpartition = 0;
        }
#endif

        /*
         * If NFS is specified as the file system, and we found
         * a DV_DISK boot device (or no boot device at all), then
         * find a reasonable network interface for "rootspec".
         */
        vops = vfs_getopsbyname(MOUNT_NFS);
        if (vops != NULL && strcmp(rootfstype, MOUNT_NFS) == 0 &&
            rootspec == NULL &&
            (bootdv == NULL || device_class(bootdv) != DV_IFNET)) {
                IFNET_FOREACH(ifp) {
                        if ((ifp->if_flags &
                             (IFF_LOOPBACK|IFF_POINTOPOINT)) == 0)
                                break;
                }
                if (ifp == NULL) {
                        /*
                         * Can't find a suitable interface; ask the
                         * user.
                         */
                        boothowto |= RB_ASKNAME;
                } else {
                        /*
                         * Have a suitable interface; behave as if
                         * the user specified this interface.
                         */
                        rootspec = (const char *)ifp->if_xname;
                }
        }
        if (vops != NULL)
                vfs_delref(vops);

        /*
         * If wildcarded root and we the boot device wasn't determined,
         * ask the user.
         */
        if (rootspec == NULL && bootdv == NULL)
                boothowto |= RB_ASKNAME;

 top:
        if (boothowto & RB_ASKNAME) {
                device_t defdumpdv;

                for (;;) {
                        printf("root device");
                        if (bootdv != NULL) {
                                printf(" (default %s", device_xname(bootdv));
                                if (DEV_USES_PARTITIONS(bootdv))
                                        printf("%c", bootpartition + 'a');
                                printf(")");
                        }
                        printf(": ");
                        len = cngetsn(buf, sizeof(buf));
                        if (len == 0 && bootdv != NULL) {
                                strlcpy(buf, device_xname(bootdv), sizeof(buf));
                                len = strlen(buf);
                        }
                        if (len > 0 && buf[len - 1] == '*') {
                                buf[--len] = '\0';
                                dv = getdisk(buf, len, 1, &nrootdev, 0);
                                if (dv != NULL) {
                                        rootdv = dv;
                                        break;
                                }
                        }
                        dv = getdisk(buf, len, bootpartition, &nrootdev, 0);
                        if (dv != NULL) {
                                rootdv = dv;
                                break;
                        }
                }

                /*
                 * Set up the default dump device.  If root is on
                 * a network device, there is no default dump
                 * device, since we don't support dumps to the
                 * network.
                 */
                if (DEV_USES_PARTITIONS(rootdv) == 0)
                        defdumpdv = NULL;
                else
                        defdumpdv = rootdv;

                for (;;) {
                        printf("dump device");
                        if (defdumpdv != NULL) {
                                /*
                                 * Note, we know it's a disk if we get here.
                                 */
                                printf(" (default %sb)", device_xname(defdumpdv));
                        }
                        printf(": ");
                        len = cngetsn(buf, sizeof(buf));
                        if (len == 0) {
                                if (defdumpdv != NULL) {
                                        ndumpdev = MAKEDISKDEV(major(nrootdev),
                                            DISKUNIT(nrootdev), 1);
                                }
                                dumpdv = defdumpdv;
                                break;
                        }
                        if (len == 4 && strcmp(buf, "none") == 0) {
                                dumpdv = NULL;
                                break;
                        }
                        dv = getdisk(buf, len, 1, &ndumpdev, 1);
                        if (dv != NULL) {
                                dumpdv = dv;
                                break;
                        }
                }

                rootdev = nrootdev;
                dumpdev = ndumpdev;

                for (vops = LIST_FIRST(&vfs_list); vops != NULL;
                     vops = LIST_NEXT(vops, vfs_list)) {
                        if (vops->vfs_mountroot != NULL &&
                            strcmp(rootfstype, vops->vfs_name) == 0)
                        break;
                }

                if (vops == NULL) {
                        deffsname = "generic";
                } else
                        deffsname = vops->vfs_name;

                for (;;) {
                        printf("file system (default %s): ", deffsname);
                        len = cngetsn(buf, sizeof(buf));
                        if (len == 0) {
                                if (strcmp(deffsname, "generic") == 0)
                                        rootfstype = ROOT_FSTYPE_ANY;
                                break;
                        }
                        if (len == 4 && strcmp(buf, "halt") == 0)
                                cpu_reboot(RB_HALT, NULL);
                        else if (len == 6 && strcmp(buf, "reboot") == 0)
                                cpu_reboot(0, NULL);
#if defined(DDB)
                        else if (len == 3 && strcmp(buf, "ddb") == 0) {
                                console_debugger();
                        }
#endif
                        else if (len == 7 && strcmp(buf, "generic") == 0) {
                                rootfstype = ROOT_FSTYPE_ANY;
                                break;
                        }
                        vops = vfs_getopsbyname(buf);
                        if (vops == NULL || vops->vfs_mountroot == NULL) {
                                printf("use one of: generic");
                                for (vops = LIST_FIRST(&vfs_list);
                                     vops != NULL;
                                     vops = LIST_NEXT(vops, vfs_list)) {
                                        if (vops->vfs_mountroot != NULL)
                                                printf(" %s", vops->vfs_name);
                                }
                                if (vops != NULL)
                                        vfs_delref(vops);
#if defined(DDB)
                                printf(" ddb");
#endif
                                printf(" halt reboot\n");
                        } else {
                                /*
                                 * XXX If *vops gets freed between here and
                                 * the call to mountroot(), rootfstype will
                                 * point to something unexpected.  But in
                                 * this case the system will fail anyway.
                                 */
                                rootfstype = vops->vfs_name;
                                vfs_delref(vops);
                                break;
                        }
                }

        } else if (rootspec == NULL) {
                /*
                 * Wildcarded root; use the boot device.
                 */
                rootdv = bootdv;

                if (bootdv)
                        majdev = devsw_name2blk(device_xname(bootdv), NULL, 0);
                else
                        majdev = -1;
                if (majdev >= 0) {
                        /*
                         * Root is on a disk.  `bootpartition' is root,
                         * unless the device does not use partitions.
                         */
                        if (DEV_USES_PARTITIONS(bootdv))
                                rootdev = MAKEDISKDEV(majdev,
                                                      device_unit(bootdv),
                                                      bootpartition);
                        else
                                rootdev = makedev(majdev, device_unit(bootdv));
                }
        } else {

                /*
                 * `root on <dev> ...'
                 */

                /*
                 * If it's a network interface, we can bail out
                 * early.
                 */
                dv = finddevice(rootspec);
                if (dv != NULL && device_class(dv) == DV_IFNET) {
                        rootdv = dv;
                        goto haveroot;
                }

                if (rootdev == NODEV &&
                    device_class(dv) == DV_DISK && device_is_a(dv, "dk") &&
                    (majdev = devsw_name2blk(device_xname(dv), NULL, 0)) >= 0)
                        rootdev = makedev(majdev, device_unit(dv));

                rootdevname = devsw_blk2name(major(rootdev));
                if (rootdevname == NULL) {
                        printf("unknown device major 0x%llx\n",
                            (unsigned long long)rootdev);
                        boothowto |= RB_ASKNAME;
                        goto top;
                }
                memset(buf, 0, sizeof(buf));
                snprintf(buf, sizeof(buf), "%s%llu", rootdevname,
                    (unsigned long long)DISKUNIT(rootdev));

                rootdv = finddevice(buf);
                if (rootdv == NULL) {
                        printf("device %s (0x%llx) not configured\n",
                            buf, (unsigned long long)rootdev);
                        boothowto |= RB_ASKNAME;
                        goto top;
                }
        }

 haveroot:

        root_device = rootdv;

        switch (device_class(rootdv)) {
        case DV_IFNET:
        case DV_DISK:
                aprint_normal("root on %s", device_xname(rootdv));
                if (DEV_USES_PARTITIONS(rootdv))
                        aprint_normal("%c", (int)DISKPART(rootdev) + 'a');
                break;

        default:
                printf("can't determine root device\n");
                boothowto |= RB_ASKNAME;
                goto top;
        }

        /*
         * Now configure the dump device.
         *
         * If we haven't figured out the dump device, do so, with
         * the following rules:
         *
         *      (a) We already know dumpdv in the RB_ASKNAME case.
         *
         *      (b) If dumpspec is set, try to use it.  If the device
         *          is not available, punt.
         *
         *      (c) If dumpspec is not set, the dump device is
         *          wildcarded or unspecified.  If the root device
         *          is DV_IFNET, punt.  Otherwise, use partition b
         *          of the root device.
         */

        if (boothowto & RB_ASKNAME) {           /* (a) */
                if (dumpdv == NULL)
                        goto nodumpdev;
        } else if (dumpspec != NULL) {          /* (b) */
                if (strcmp(dumpspec, "none") == 0 || dumpdev == NODEV) {
                        /*
                         * Operator doesn't want a dump device.
                         * Or looks like they tried to pick a network
                         * device.  Oops.
                         */
                        goto nodumpdev;
                }

                dumpdevname = devsw_blk2name(major(dumpdev));
                if (dumpdevname == NULL)
                        goto nodumpdev;
                memset(buf, 0, sizeof(buf));
                snprintf(buf, sizeof(buf), "%s%llu", dumpdevname,
                    (unsigned long long)DISKUNIT(dumpdev));

                dumpdv = finddevice(buf);
                if (dumpdv == NULL) {
                        /*
                         * Device not configured.
                         */
                        goto nodumpdev;
                }
        } else {                                /* (c) */
                if (DEV_USES_PARTITIONS(rootdv) == 0) {
                        for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST);
                             dv != NULL;
                             dv = deviter_next(&di))
                                if (isswap(dv))
                                        break;
                        deviter_release(&di);
                        if (dv == NULL)
                                goto nodumpdev;

                        majdev = devsw_name2blk(device_xname(dv), NULL, 0);
                        if (majdev < 0)
                                goto nodumpdev;
                        dumpdv = dv;
                        dumpdev = makedev(majdev, device_unit(dumpdv));
                } else {
                        dumpdv = rootdv;
                        dumpdev = MAKEDISKDEV(major(rootdev),
                            device_unit(dumpdv), 1);
                }
        }

        dumpcdev = devsw_blk2chr(dumpdev);
        aprint_normal(" dumps on %s", device_xname(dumpdv));
        if (DEV_USES_PARTITIONS(dumpdv))
                aprint_normal("%c", (int)DISKPART(dumpdev) + 'a');
        aprint_normal("\n");
        return;

 nodumpdev:
        dumpdev = NODEV;
        dumpcdev = NODEV;
        aprint_normal("\n");
}

static device_t
finddevice(const char *name)
{
        const char *wname;

        if ((wname = getwedgename(name, strlen(name))) != NULL)
                return dkwedge_find_by_wname(wname);

        return device_find_by_xname(name);
}

static device_t
getdisk(char *str, int len, int defpart, dev_t *devp, int isdump)
{
        device_t dv;
        deviter_t di;

        if ((dv = parsedisk(str, len, defpart, devp)) == NULL) {
                printf("use one of:");
                for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST); dv != NULL;
                     dv = deviter_next(&di)) {
                        if (DEV_USES_PARTITIONS(dv))
                                printf(" %s[a-%c]", device_xname(dv),
                                    'a' + MAXPARTITIONS - 1);
                        else if (device_class(dv) == DV_DISK)
                                printf(" %s", device_xname(dv));
                        if (isdump == 0 && device_class(dv) == DV_IFNET)
                                printf(" %s", device_xname(dv));
                }
                deviter_release(&di);
                dkwedge_print_wnames();
                if (isdump)
                        printf(" none");
#if defined(DDB)
                printf(" ddb");
#endif
                printf(" halt reboot\n");
        }
        return dv;
}

static const char *
getwedgename(const char *name, int namelen)
{
        const char *wpfx = "wedge:";
        const int wpfxlen = strlen(wpfx);

        if (namelen < wpfxlen || strncmp(name, wpfx, wpfxlen) != 0)
                return NULL;

        return name + wpfxlen;
}

static device_t
parsedisk(char *str, int len, int defpart, dev_t *devp)
{
        device_t dv;
        const char *wname;
        char *cp, c;
        int majdev, part;
        if (len == 0)
                return (NULL);

        if (len == 4 && strcmp(str, "halt") == 0)
                cpu_reboot(RB_HALT, NULL);
        else if (len == 6 && strcmp(str, "reboot") == 0)
                cpu_reboot(0, NULL);
#if defined(DDB)
        else if (len == 3 && strcmp(str, "ddb") == 0)
                console_debugger();
#endif

        cp = str + len - 1;
        c = *cp;

        if ((wname = getwedgename(str, len)) != NULL) {
                if ((dv = dkwedge_find_by_wname(wname)) == NULL)
                        return NULL;
                part = defpart;
                goto gotdisk;
        } else if (c >= 'a' && c <= ('a' + MAXPARTITIONS - 1)) {
                part = c - 'a';
                *cp = '\0';
        } else
                part = defpart;

        dv = finddevice(str);
        if (dv != NULL) {
                if (device_class(dv) == DV_DISK) {
 gotdisk:
                        majdev = devsw_name2blk(device_xname(dv), NULL, 0);
                        if (majdev < 0)
                                panic("parsedisk");
                        if (DEV_USES_PARTITIONS(dv))
                                *devp = MAKEDISKDEV(majdev, device_unit(dv),
                                                    part);
                        else
                                *devp = makedev(majdev, device_unit(dv));
                }

                if (device_class(dv) == DV_IFNET)
                        *devp = NODEV;
        }

        *cp = c;
        return (dv);
}

/*
 * Return true if system call tracing is enabled for the specified process.
 */
bool
trace_is_enabled(struct proc *p)
{
#ifdef SYSCALL_DEBUG
        return (true);
#endif
#ifdef KTRACE
        if (ISSET(p->p_traceflag, (KTRFAC_SYSCALL | KTRFAC_SYSRET)))
                return (true);
#endif
#ifdef PTRACE
        if (ISSET(p->p_slflag, PSL_SYSCALL))
                return (true);
#endif

        return (false);
}

/*
 * Start trace of particular system call. If process is being traced,
 * this routine is called by MD syscall dispatch code just before
 * a system call is actually executed.
 */
int
trace_enter(register_t code, const register_t *args, int narg)
{
#ifdef SYSCALL_DEBUG
        scdebug_call(code, args);
#endif /* SYSCALL_DEBUG */

        ktrsyscall(code, args, narg);

#ifdef PTRACE
        if ((curlwp->l_proc->p_slflag & (PSL_SYSCALL|PSL_TRACED)) ==
            (PSL_SYSCALL|PSL_TRACED))
                process_stoptrace();
#endif
        return 0;
}

/*
 * End trace of particular system call. If process is being traced,
 * this routine is called by MD syscall dispatch code just after
 * a system call finishes.
 * MD caller guarantees the passed 'code' is within the supported
 * system call number range for emulation the process runs under.
 */
void
trace_exit(register_t code, register_t rval[], int error)
{
#ifdef SYSCALL_DEBUG
        scdebug_ret(code, error, rval);
#endif /* SYSCALL_DEBUG */

        ktrsysret(code, error, rval);
        
#ifdef PTRACE
        if ((curlwp->l_proc->p_slflag & (PSL_SYSCALL|PSL_TRACED)) ==
            (PSL_SYSCALL|PSL_TRACED))
                process_stoptrace();
#endif
}

int
syscall_establish(const struct emul *em, const struct syscall_package *sp)
{
        struct sysent *sy;
        int i;

        KASSERT(mutex_owned(&module_lock));

        if (em == NULL) {
                em = &emul_netbsd;
        }
        sy = em->e_sysent;

        /*
         * Ensure that all preconditions are valid, since this is
         * an all or nothing deal.  Once a system call is entered,
         * it can become busy and we could be unable to remove it
         * on error.
         */
        for (i = 0; sp[i].sp_call != NULL; i++) {
                if (sy[sp[i].sp_code].sy_call != sys_nomodule) {
#ifdef DIAGNOSTIC
                        printf("syscall %d is busy\n", sp[i].sp_code);
#endif
                        return EBUSY;
                }
        }
        /* Everything looks good, patch them in. */
        for (i = 0; sp[i].sp_call != NULL; i++) {
                sy[sp[i].sp_code].sy_call = sp[i].sp_call;
        }

        return 0;
}

int
syscall_disestablish(const struct emul *em, const struct syscall_package *sp)
{
        struct sysent *sy;
        uint64_t where;
        lwp_t *l;
        int i;

        KASSERT(mutex_owned(&module_lock));

        if (em == NULL) {
                em = &emul_netbsd;
        }
        sy = em->e_sysent;

        /*
         * First, patch the system calls to sys_nomodule to gate further
         * activity.
         */
        for (i = 0; sp[i].sp_call != NULL; i++) {
                KASSERT(sy[sp[i].sp_code].sy_call == sp[i].sp_call);
                sy[sp[i].sp_code].sy_call = sys_nomodule;
        }

        /*
         * Run a cross call to cycle through all CPUs.  This does two
         * things: lock activity provides a barrier and makes our update
         * of sy_call visible to all CPUs, and upon return we can be sure
         * that we see pertinent values of l_sysent posted by remote CPUs.
         */
        where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
        xc_wait(where);

        /*
         * Now it's safe to check l_sysent.  Run through all LWPs and see
         * if anyone is still using the system call.
         */
        for (i = 0; sp[i].sp_call != NULL; i++) {
                mutex_enter(proc_lock);
                LIST_FOREACH(l, &alllwp, l_list) {
                        if (l->l_sysent == &sy[sp[i].sp_code]) {
                                break;
                        }
                }
                mutex_exit(proc_lock);
                if (l == NULL) {
                        continue;
                }
                /*
                 * We lose: one or more calls are still in use.  Put back
                 * the old entrypoints and act like nothing happened.
                 * When we drop module_lock, any system calls held in
                 * sys_nomodule() will be restarted.
                 */
                for (i = 0; sp[i].sp_call != NULL; i++) {
                        sy[sp[i].sp_code].sy_call = sp[i].sp_call;
                }
                return EBUSY;
        }

        return 0;
}