kern/153804: boot from zfs kernel.old recovery undocumented/impossible

[Nick Sayer]

The following reply was made to PR kern/153804; it has been noted by GNATS.

From: Nick Sayer <nsayer at kfu.com>
To: Pan Tsu <inyaoo at gmail.com>
Cc: Andriy Gapon <avg at FreeBSD.org>, bug-followup at FreeBSD.org
Subject: Re: kern/153804: boot from zfs kernel.old recovery undocumented/impossible
Date: Wed, 25 May 2011 07:21:40 -0700

 On May 25, 2011, at 1:52 AM, Pan Tsu wrote:
 
 > Andriy Gapon <avg at FreeBSD.org> writes:
 >=20
 >> Try the following options:
 >>=20
 >> 1)
 >> unload
 >> set kernel=3Dkernel.old
 >> boot
 >>=20
 >> 2)
 >> unload
 >> load /boot/kernel.old/kernel
 >> load -t /boot/zfs/zpool.cache /boot/zfs/zpool.cache
 >=20
 > zpool_cache_type can be anything. loader(8) unlike grub2 doesn't =
 enforce
 > type to be "/boot/zfs/zpool.cache".
 >=20
 >> boot
 >=20
 > Whatever happened to just typing following?
 >=20
 >  boot kernel.old
 >=20
 > It assumes zpool.cache was already preloaded by failed attempt to boot
 > default kernel. No need to `unload' the kernel, `boot' replaces it.
 
 I didn't try that. At the time I didn't think it worked that way. Back =
 when I was in full on panic mode, I think option number 1 was what =
 finally worked, but I am happier with option 2, as it offers the most =
 control. It just needs to be better documented.
 
 >=20
 >> My expectation is that both should do what you want.