Re: software reset

[H. Peter Anvin]

Followup to:  <[e-mail]>
By author:    Andi Kleen <[e-mail]>
In newsgroup: linux.dev.kernel
>
> joe briggs <[e-mail]> 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.
> 

Except that isn't actually a reset -- it's an INIT, which isn't quite
the same thing; for one thing, the hardware isn't forcibly reset.

On *MOST*, but definitely not ALL, chipsets you can force a "true"
reset by writing 0x06 to I/O port 0x0CF9.

	-hpa
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