From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.71) id 1U3rHW-0007jl-Mw for mharc-grub-devel@gnu.org; Fri, 08 Feb 2013 11:58:34 -0500 Received: from eggs.gnu.org ([208.118.235.92]:45181) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U3rGw-0007Z1-BS for grub-devel@gnu.org; Fri, 08 Feb 2013 11:58:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1U3rGT-0002XT-9F for grub-devel@gnu.org; Fri, 08 Feb 2013 11:57:58 -0500 Received: from mail-ea0-f172.google.com ([209.85.215.172]:45062) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U3rGS-0002XF-VY for grub-devel@gnu.org; Fri, 08 Feb 2013 11:57:29 -0500 Received: by mail-ea0-f172.google.com with SMTP id f13so1793128eaa.31 for ; Fri, 08 Feb 2013 08:57:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=F7FQCUfVdIO0Z01j1PliW1eEkkIkkOSr0DOkrYp0N/s=; b=ZUav07eEinYZ453+apFatbDDaQ44F3Pqxa6myCVz8+BJj0bsy1eudUoe2x1TS43AY2 HH79z1Wbn78gnl5H6+t4pPM+lT70df/tLKB1hF/3vr/K+XFTLCAFemqIpj2bcx0DdWdw WZNZxWDKcoJh7FcCkefuB5oBmVVnD8yPom9uv4YV00k97maaSA5Xuz3mbznjdxRG56u6 HiS2/9PLv6/9wc4/gS4wbYpJbsi01gkanZyJARdtvkD6KOCaIDVJpw5A2bCKLMYzMPsj xVzK1FhpB9EFQuMS9DwYsfAzCoQADLx0sGADz3zvxlwwPWtwSkWWhF9LEnw+1oikymj8 lKag== MIME-Version: 1.0 X-Received: by 10.14.179.5 with SMTP id g5mr17690372eem.41.1360342647392; Fri, 08 Feb 2013 08:57:27 -0800 (PST) Received: by 10.223.80.10 with HTTP; Fri, 8 Feb 2013 08:57:27 -0800 (PST) Received: by 10.223.80.10 with HTTP; Fri, 8 Feb 2013 08:57:27 -0800 (PST) In-Reply-To: <51138645.4050405@ts.fujitsu.com> References: <51138645.4050405@ts.fujitsu.com> Date: Fri, 8 Feb 2013 17:57:27 +0100 Message-ID: Subject: Re: GRUB and the risk of block list corruption in extX From: "Vladimir 'phcoder' Serbinenko" To: The development of GNU GRUB Content-Type: multipart/alternative; boundary=047d7b603fe64547c304d53974ac X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 209.85.215.172 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 Feb 2013 16:58:32 -0000 --047d7b603fe64547c304d53974ac Content-Type: text/plain; charset=ISO-8859-1 This is not a complete answer but one of my problems is that such requests don't even suply any kind of reason to go into such installs. We nerd to consider usecases before even considering using an approach which is known for some pretty serious problems. Will answer in more details later. On Feb 7, 2013 11:47 AM, "Martin Wilck" wrote: > Hello, > > this is a question about the long-running topic of installing GRUB in > partitions or partitionless disks. > > Recently I have been involved in discussions about this on > https://bugzilla.redhat.com/show_bug.cgi?id=872826. The Fedora boot > loader can't be installed in partition headers any more. The major > reason given by the Fedora developers is the famous GRUB warning > "blocklists are UNRELIABLE and their use is discouraged." > > The Grub manual says "installing to a filesystem means that GRUB is > vulnerable to its blocks being moved around by filesystem features such > as tail packing, or even by aggressive fsck implementations". > > I'd like to understand how this blocklist corruption might come to pass > (except for cases where "core.img" itself is moved, deleted, or > overwritten by user space tools). Also, it has been recommended to > prevent accidental corruption by setting the IMMUTABLE flag on core.img, > and I'd like to ask for the GRUB experts' opinion about that. > Finally I'd like to know if it's true that the GRUB team plans to drop > block list support altogether in a future version. > > Regards > Martin Wilck > > PS: It has been stated that of recent filesystems, this matters most for > extX, because btrfs has a 64k header where embedding GRUB is usually > possible. Therefore I asked a similar question on ext4-devel. > > > > -- > Dr. Martin Wilck > PRIMERGY System Software Engineer > x86 Server Engineering > > FUJITSU > Fujitsu Technology Solutions GmbH > Heinz-Nixdorf-Ring 1 > 33106 Paderborn, Germany > Phone: ++49 5251 525 2796 > Fax: ++49 5251 525 2820 > Email: martin.wilck@ts.fujitsu.com > Internet: http://ts.fujitsu.com > Company Details: http://ts.fujitsu.com/imprint > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel > --047d7b603fe64547c304d53974ac Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

This is not a complete answer but one of my problems is that such reques= ts don't even suply any kind of reason to go into such installs. We ner= d to consider usecases before even considering using an approach which is k= nown for some pretty serious problems. Will answer in more details later.

On Feb 7, 2013 11:47 AM, "Martin Wilck"= ; <martin.wilck@ts.fujits= u.com> wrote:
Hello,

this is a question about the long-running topic of installing GRUB in
partitions or partitionless disks.

Recently I have been involved in discussions about this on
https://bugzilla.redhat.com/show_bug.cgi?id=3D872826. The Fedor= a boot
loader can't be installed in partition headers any more. The major
reason given by the Fedora developers is the famous GRUB warning
"blocklists are UNRELIABLE and their use is discouraged."

The Grub manual says "installing to a filesystem means that GRUB is vulnerable to its blocks being moved around by filesystem features such
as tail packing, or even by aggressive fsck implementations".

I'd like to understand how this blocklist corruption might come to pass=
(except for cases where "core.img" itself is moved, deleted, or overwritten by user space tools). Also, it has been recommended to
prevent accidental corruption by setting the IMMUTABLE flag on core.img, and I'd like to ask for the GRUB experts' opinion about that.
Finally I'd like to know if it's true that the GRUB team plans to d= rop
block list support altogether in a future version.

Regards
Martin Wilck

PS: It has been stated that of recent filesystems, this matters most for extX, because btrfs has a 64k header where embedding GRUB is usually
possible. Therefore I asked a similar question on ext4-devel.



--
Dr. Martin Wilck
PRIMERGY System Software Engineer
x86 Server Engineering

FUJITSU
Fujitsu Technology Solutions GmbH
Heinz-Nixdorf-Ring 1
33106 Paderborn, Germany
Phone: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0++49 5251 525 2796
Fax: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0++49 5251 525 2820
Email: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0martin.wilck@ts.fujitsu.com
Internet: =A0 =A0 =A0 =A0 =A0 =A0 =A0 http://ts.fujitsu.com
Company Details: =A0 =A0 =A0 =A0http://ts.fujitsu.com/imprint

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