Date: Mon, 25 Aug 2014 10:38:40 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: "Andrey V. Elsukov" <bu7cher@yandex.ru> Cc: Craig Rodrigues <rodrigc@freebsd.org>, freebsd-current Current <freebsd-current@freebsd.org>, Marcel Moolenaar <marcel@xcllnt.net> Subject: Re: mkimg used to create gpt image, problem booting Message-ID: <20140825173840.GT71691@funkthat.com> In-Reply-To: <53FB5014.40402@yandex.ru> References: <CAG=rPVe8Lh=P2MUdycM7%2B2mpSBPhe%2BkTvxR_bjnZfB1EkvK92Q@mail.gmail.com> <53F9AC50.1000000@yandex.ru> <CAG=rPVctN4-UBxRzWhEoEt5e_4d8UXCa0O40LZUHnS5Qj9hFeA@mail.gmail.com> <82000B55-10E5-4348-9F35-38962965A63C@xcllnt.net> <CAG=rPVeLgOGXx8=S18u03JuNGB9PzYk3uYZS8r=sgu3b_UHOmQ@mail.gmail.com> <20140824233143.GQ71691@funkthat.com> <3AC10D0D-2BD8-4D30-A033-7EE9D923F408@xcllnt.net> <53FAEA31.1070108@yandex.ru> <B44B1E51-0F9E-41ED-B37F-DA2A9E6334FC@xcllnt.net> <53FB5014.40402@yandex.ru>
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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."
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