Re: mkimg used to create gpt image, problem booting

From: John-Mark Gurney <jmg_at_funkthat.com>
Date: Mon, 25 Aug 2014 10:38:40 -0700
Andrey V. Elsukov wrote this message on Mon, Aug 25, 2014 at 19:02 +0400:
> On 25.08.2014 18:40, Marcel Moolenaar wrote:
> >> Also, now FreeBSD 11.0 uses different first usable LBA. By default it is
> >> 4k aligned. And this creates some incompatibility with older versions.
> >> You can't do `gpart restore` and get the same table, as you had on older
> >> system.
> > 
> > It sounds restore is broken then. The restore command
> > cannot ever assume anything about the GPT. Including
> > the tool that created the GPT. In order to restore a
> > GPT, it must be properly backed-up. The backup header
> > and table should suffice most of the time for that
> > purpose as it's a replica, but as soon as meta-data is
> > missing and the restore command has to guess, things
> > will go wrong.
> 
> `gpart restore` just uses a number of commands to geom_part(4) to create
> partition table similar to what was backed up. If your partition table
> on the old system had a partition that starts from LBA 34, now `gpart
> create` isn't able to create such partition table. Because by default
> the first usable LBA is 40.

Luckily, gpart restore won't work:
# gpart backup /dev/md0
GPT 4
1 freebsd-ufs      8 262144  
# gpart restore md1 < /tmp/foob.gpt.back 
gpart: entries '4': Invalid argument

So, we're somewhat safe, guess gpart restore needs to learn how to
handle entries properly....

We should fix this, since other OS's might not use 128 for entries..

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."
Received on Mon Aug 25 2014 - 15:38:43 UTC

This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:40:51 UTC