Newbie Question About System Update

Jean-Simon jsimon at
Tue Apr 19 14:55:55 PDT 2005


If you are working with a remote system, you should probably be using the
"nextboot" utility for testing a new kernel after your "make buildworld",
"make buildkernel" and "make installkernel".

>From nextboot's man page :
     The nextboot utility allows specifying an alternate kernel and/or boot
     flags for the next time the machine is booted.  Once the loader(8)
     in the new kernel information, it is deleted so in case the new kernel
     hangs the machine, once it is rebooted, the machine will automatically
     revert to its previous configuration.

Just rename your new kernel and put back the backup as the default. You
should probably also edit '/etc/rc.conf' to disable your services (except
sshd of course! :D). Then, proceed with "nextboot -k $newkernelname".

If everything works fine, you can set the new kernel as the default and
finish your update with "mergemaster -p", "make installworld" and
"mergemaster". If your are confident, you can reanable all your services in
'/etc/rc.conf' and reboot one last time. Otherwise, you can test your
services and reenable them one by one.

WARNING: Bad things may and will probably happen if you forget to set your
new kernel as the default after finishing your update. Your system might not
come back online on your next reboot because you will have an old kernel
with new system binaries.

Have fun!


----- Original Message ----- 
From: "Kent Stewart" <kstewart at>
To: <freebsd-stable at>
Cc: "Dan Nelson" <dnelson at>; "Bill Moran"
<wmoran at>
Sent: Tuesday, April 19, 2005 5:02 PM
Subject: Re: Newbie Question About System Update

> On Tuesday 19 April 2005 01:39 pm, Dan Nelson wrote:
> You are forgetting that one of the real purposes of the boot -s is to
> test your new kernel. If you have never been bitten by a kernel that
> would only panic, you have no problems. If you have, you know that you
> can boot the old kernel and continue without any problems until some
> one solves the panic. You will not most likely hit that situation on a
> security based version but this is freebsd-stable and it can happen at
> any time.
> My attitude is that if you don't boot -s, you are simply playing
> Russian-roulette with your system. Some day, it will bite you.
> Kent

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