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Date:      Tue, 28 Aug 2012 14:12:10 -0700
From:      Freddie Cash <fjwcash@gmail.com>
To:        Kevin Oberman <kob6558@gmail.com>
Cc:        Jamie Paul Griffin <jamie@kode5.net>, freebsd-stable@freebsd.org
Subject:   Re: Question About Tracking the Stable Branch
Message-ID:  <CAOjFWZ7HM2Z4FqPeoJ2c1qbX1DaygGGg5CLJh%2BytDs4wjBfVFg@mail.gmail.com>
In-Reply-To: <CAN6yY1tKTu2mRaDo1WyNtvv7Sw5yFuTrru2QyGvD8jQg1oZ%2BPw@mail.gmail.com>
References:  <20120828203130.GB78051@kontrol.kode5.net> <CAN6yY1tKTu2mRaDo1WyNtvv7Sw5yFuTrru2QyGvD8jQg1oZ%2BPw@mail.gmail.com>

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On Tue, Aug 28, 2012 at 2:03 PM, Kevin Oberman <kob6558@gmail.com> wrote:
> In all cases, if you rebuild the kernel, be sure that the old kernel
> is saved to kernel.old so you can go back to it if there si a problem.
> 'make installkernel' does this) and, should you fix a problem and
> re-link the kernel, be sure NOT to overwrite the working kernel ('make
> reinstallkernel' does this.

It's not mentioned often on the lists, but KODIR and nextboot(8) are
wonderful things:
  # make <whatever options> buildworld
  # make KERNCONF=MYKERNEL <whatever other options> buildkernel
  # make KERNCONF=MYKERNEL KODIR=/boot/MYKERNEL <whatever other
options> installkernel
  # nextboot -k MYKERNEL
  # shutdown -r now

That will install your new kernel into /boot/MYKERNEL, leaving
/boot/kernel alone.  nextboot configures the boot process to use
/boot/MYKERNEL, again leaving /boot/kernel along.  If anything goes
wrong, a simple reboot of the box returns you to using /boot/kernel as
before.

If the new kernel works correctly, then you can manually copy/moves
things around as needed:
  # mv /boot/kernel /boot/kernel.old
  # cp -Rvp /boot/MYKERNEL /boot/kernel

Especially useful when testing new kernels on remote systems, as "hit
the reset switch" on a locked up box puts things back to the way they
were before.  No loader commands required.  :)

-- 
Freddie Cash
fjwcash@gmail.com



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