How do I do a COLD Reboot on FreeBSD?
jerrymc at clunix.cl.msu.edu
Mon Jan 31 07:58:34 PST 2005
> Jerry McAllister wrote:
> >>I need to do a cold restart. I've looked through a lot of docs, and I
> >>seem to find this out. The computer I am working with seems to no longer
> >>enjoy a warm reboot (like "shutdown -r now" or "reboot") but I'm pretty
> >>it will do cold reboots fine. Is there a port, or is the shutdown command
> >>hackable for this, or what?
> >>I remember many computers in bygone years which had this problem. It was
> >>pretty common back in the 90's it seems like. Computers would reboot and
> >>weird using CTRL-ALT-DELETE, but work fine when powered off and on.
> > FreeBSD is pretty good about doing a very clean reboot as far as the OS
> > is concerned. But, it is possible that some devices don't clean up well
> > in ways that are out of FreeBSD control. So, a "cold boot" can be a
> > good idea in some circumstances.
> > To do this, do a 'shutdown -h now' or a 'shutdown -p now' if your
> > hardware supports the -p and you have it set up. Choose your own
> > time of delay for 'now' if you have other people on the machine.
> > If you did the '-h' or the '-p' didn't turn off the power, then
> > at the "press any key to reboot" prompt, turn off the power.
> > Then, unplug the power source and let it set for a few minutes to let
> > any charge dissipate. This can be important because the capacitance
> > in some of the devices including the power supply can provide just
> > enough charge to keep them from reloading if that is their inclination
> > and you lose the effect you are looking for. You should also unplug
> > the network connection and any external devices that have their own
> > power supply.
> I know that this is all very good advice and information from the shutdown
> man page and good stuff about the nature of capacitors, but all of this is
> known to myself and unfortunately not useful... The shutdown -p does
> essentially a different thing (and one time it caused the freeze problem to
> disappear.) but this also does not work. I don't want to shut the computer
> off, anyway, I want it to reboot back to FreeBSD remotely if need be.
> And so far, the halt command (or its shutdown -h equivalent) is not what I
> want, either. If I press a key to reboot, I get the same issue anyway.
> There's a remote possibility that the halt code is causing the freeze up,
> because FreeBSD 4.7 did not have this problem. I'm not confident whether the
> machine broke or the new 5.3 code broke, so I won't speculate which. I just
> need the reboot code.
> > After a sufficient time drain capacitance - I usually go to the bathroom
> > or go get something to drink to kill a few minutes - , then just plug
> > it all back in. Plug in the network cable and any external devices first
> > and then the power cord and turn it on and let it boot.
> It's not the capacitors, but perhaps some strange bug in the BIOS or
> something, I guess. The issue that I'm highlighting is that when a floppy
> program does a cold reset of this machine, the system (re)boots normally.
Well, I guess I completely do not understand what you are asking.
>From anything I can get from what you write here, its behavior is
normal and expected. What is the problem and what are you trying
to fix or to get it to do?
A cold boot - which is what you ask about in your original post - is
a boot all the way up from a powered off machine as far as I know.
So, all I did was explain how to get what you asked for in the post.
Another small guess - are you looking for 'shutdown -r now' by
If you want something else, you will need to explain that. Who knows
if anyone will know what to do about that - at least not until you
reveal what it is.
> As a side note, I have run this machine through the ringer trying to discover
> any hardware errors. The memory is now EDO ECC (it had been something else)
> and the problem persists. I have run diagnostics, memtest86, etc. Futile.
> The cold reset code exists somewhere. Anybody?
> > Voila, you have gone from warm to cold to warm again.
> > ////jerry
> >>The computer I've got actually fails a memory test during the warm reboot.
> >>This freezes it. I have to power cycle the machine. And then, the computer
> >>performs a warm restart, bypassing its memory checks! One more power cycle
> >>laster, it will boot normally. If I don't do this last reboot, the FreeBSD
> >>boot loader or the beginning of the kernel boot crashes very early. It's
> >>stable otherwise on a cold reboot.
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