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Date: Mon, 30 Jul 2012 18:17:27 +0200
From: Paul Schenkeveld <freebsd@psconsult.nl>
To: freebsd-geom@freebsd.org
Message-ID: <20120730161727.GA90551@psconsult.nl>
References: <803675128.20120730002927@serebryakov.spb.ru>
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Subject: Re: "nextboot" for MBR slice?
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On Mon, Jul 30, 2012 at 12:29:27AM +0400, Lev Serebryakov wrote:
> Hello, Freebsd-geom.
> 
>   Is it possible to implement something like "nextboot" for MBR
> slice?

I don't know of such implementation.

>   I have typical NanoBSD installation: CF card divided into tow slices
>  (ad1 and ad2), standard boot0 (as "smart" boot0 with partition
>  selection doesn't play well with serial console), each slice contains
>  full NanoBSD installation, current one and previous one. When I need
>  upgrade "firmware" I dd new image on "previous" slice and set
>  active bit in MBR (with gpart set -a active) to it, reboot.

Did you try to use boot0sio?  I run dozens of NanoBSD systems, most are
Soekris hardware with serial console, system on flash (CF, mSATA or
soldered on the mainboard) so that matches the hardware you describe.

There was a change in the working of boot0 and boot0sio a couple of
years ago.  Before the change (FB <= 7) one would use boot0cfg to
change the active partition.  Now (FB >= 8) one should use 'gpart set
-a active -i <slice>'.  The default slice reported during boot can be
misleading after changing the active slice with gpart but you can
still use the serial terminal to switch boot partitions.

HTH,

Paul Schenkeveld