Re: software reset

[Andi Kleen <ak@suse.de>]

joe briggs <jbriggs@briggsmedia.com> writes:

> Can anyone tell me how to absolutely force a reset on a i386?  Specifically, 
> is there a system call that will call the assembly instruction to assert the 
> RESET bus line? I try to use the "reboot(LINUX_REBOOT_CMD_RESTART,0,0,NULL)" 
> call, but it will not always work.  Occassionally, I experience a "missed 
> interrupt" on a Promise IDE controller, and while I can telnet into the 
> system, I can't reset it.  Any help greatly appreciated!  Since these systems 
> are 1000's of miles away, the need to remotely reset it paramont.

The most reliable way is to force a triple fault; load zero into
the IDT register and then trigger an exception. The linux kernel 
does that in fact for reboot and so far I haven't seen any machine failing
to reset yet.

-Andi

If you don't trust reboot you can use something like (untested!).
Compile with -c and load with insmod. I'm pretty sure it will reset
your box.

#define MODULE 1
#define __KERNEL__ 1
#include <linux/module.h>

int init_module(void)
{ 
        static struct { 
                short limit;
                unsigned ptr;
        } desc = { 64000, 0 }; 

        asm volatile("lidt %0" : "m" (desc)); 
        asm volatile("movl %0,%%esp ; int $3" : "g" (0)); 
}