Rebooting/Halting system from kernel module

[Daniel O'Connor]

On 23/01/2012, at 13:33, Andrew Davis wrote:

>> do you want to sync the disks first? of just hard reset?
> 
> Why would anyone ever want to do that, you're a kernel mod, if you want to
> do that just triple-fault.

You can call cpu_reset().

I wrote a KLD which did this because we had a driver issue where the system wouldn't reboot if you did shutdown -r (it would hang).

==== reset.c ====
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <machine/cpu.h>

static int reset_handler(module_t mod, int /*modeventtype_t*/ what,
		       void *arg);

static moduledata_t mod_data= {
    "reset",
    reset_handler,
    0
};

MODULE_VERSION(reset, 1);

DECLARE_MODULE(reset, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);

static int 
reset_handler(module_t mod, int /*modeventtype_t*/ what, void *arg) {
    switch (what) {
	case MOD_LOAD:
	    printf("Forced reboot\n");
	    DELAY(1000000); /* wait 1 sec for printf's to complete and be read */
	    /* cpu_boot(howto); */ /* doesn't do anything at the moment */
	    cpu_reset();
	    printf("Reset failed!\n");
	    /* NOTREACHED */ /* assuming reset worked */
	    break;
	    
	default:
	    return(EOPNOTSUPP);
	    break;
    }

    return(ENXIO);
}
====

==== Makefile ====
KMOD	= reset
SRCS	= reset.c

.include <bsd.kmod.mk>
====


> On Sun, Jan 22, 2012 at 9:32 PM, Julian Elischer <julian at freebsd.org> wrote:
> 
>> On 1/22/12 2:19 AM, geoffrey levand wrote:
>> 
>>> Hi,
>>> 
>>> how would i reboot/halt the system from a kernel module ?
>>> 
>> 
>> the answer is "that depends"..
>> 
>> do you want to sync the disks first? of just hard reset?
>> 
>> 
>> 
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--
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
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