Re: Minor request for enhancement: "beep on halt"

Richard Gooch (rgooch@atnf.csiro.au)
Tue, 15 Dec 1998 10:41:32 +1100


Jason A. Pfeil writes:
> Verified. You can pass shutdown the -n argument and it handles everything
> itself. Otherwise, init handles the shutdown. The second (init) method
> is the recommended method. This functionality might be able to be
> inserted into init instead of the kernel.
>
> On Mon, 14 Dec 1998, Jason A. Pfeil wrote:
>
> > In addition to this, on the manpage for shutdown(8), it states that
> > shutdown triggers the init process to handle the shutdown. shutdown(8)
> > itself handling the killing of processes is deprecated and not recommended
> > as it is not predictable. I am in the process of verifying this by
> > looking at the SRPM from RedHat5.2.

No, this may only apply in the SysV init world. For a non-SysV init,
it is perfectly legitimate to have shutdown(8) do the real work.

> > On Mon, 14 Dec 1998, Stephen Harris wrote:
> >
> > > Richard Gooch writes:
> > > > Jason A. Pfeil writes:
> > >
> > > > > Shutdown just calls a routine in the kernel to handle the shutdown before
> > > > > it is killed itself. Therefore, this ability needs to be in the kernel
> > >
> > > > Sorry, I don't agree. The shutdown(8) programme is what kills all
> > > > processes, unmounts filesystems, remounts the root FS read-only, syncs
> > > > the discs and then calls reboot(2) which halts/reboots.
> > >
> > > Could this code be in shutdown(8) ? Hmm, no... there is always the
> > > possibility that the kernel may need to perform some other "clean up" work.
> > > Surely this is the concept behind the notifier_call_chain() calls inside
> > > sys_reboot().
> > >
> > > For example, the wdt driver turns off the card at shutdown time. If the
> > > shutdown(8) program never calls sys_reboot() then the card is never turned
> > > off, and a watchdog reset could occur. Not good :-) It could cause a
> > > reboot! Some other drivers also hook into the reboot_notifier_list to
> > > perform a cleanup on shutdown.

Hm. Point taken.

Regards,

Richard....

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