From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id D505A81EEE for ; Thu, 24 Nov 2016 00:27:57 -0800 (PST) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1E82E3BEDF; Thu, 24 Nov 2016 08:27:57 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-81.phx2.redhat.com [10.3.116.81]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uAO8RswT031305; Thu, 24 Nov 2016 03:27:55 -0500 To: Rebecca Cran , Michael Zimmermann References: <2ee033d3-bf24-6710-3f72-14bd0e6dfed9@akeo.ie> <98271ced-83d5-d4e9-6b8d-416265054906@rodsbooks.com> <1bd2e268-9a18-6fc1-419d-e50d0e08f6f1@redhat.com> <4ad578ff-529b-a1bd-7211-73515527d81d@bluestop.org> Cc: Rod Smith , "edk2-devel@lists.01.org" , Marcin Wojtas , Pete Batard From: Laszlo Ersek Message-ID: <9da9e2ab-847e-3a8e-83d3-f079eaa5998d@redhat.com> Date: Thu, 24 Nov 2016 09:27:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.0 MIME-Version: 1.0 In-Reply-To: <4ad578ff-529b-a1bd-7211-73515527d81d@bluestop.org> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 24 Nov 2016 08:27:57 +0000 (UTC) Subject: Re: EXT FS support X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Nov 2016 08:27:57 -0000 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 11/24/16 02:03, Rebecca Cran wrote: > On 11/23/16 1:11 PM, Laszlo Ersek wrote: > >>>> Separately, a small note on ext4 (because you mention it above). I >>>> seem to recall a filesystem expert colleague of mine advise >>>> *against* using journaled filesystems for booting with e.g. grub2. >>>> The argument goes (if I recall right), XFS is considered to be in >>>> clean state if the data has made it to the final location *or* the >>>> persistent journal. When you cleanly unmount (or remount r/o) and >>>> shut down, the journal will be flushed to the final location, so a >>>> boot loader that doesn't know about the journal will read consistent >>>> data. However, if you crash *without* data loss, then part of the >>>> data might be in the journal only, and only clients that can read >>>> the journal will see consistent data. >>>> >>>>> This might or might not be >>>>> an issue, depending on what the point of the exercise is. > > > The problem of course is that "reset" (reboot), "reset -s" (shutdown) > etc. don't have any hooks a driver can use to flush data, so there will > sometimes (depending on how long ago data was written) be an unclean > unmount. At least when booting an OS there's an ExitBootServices event > available to make sure any data is flushed before boot services ends. Related: https://bugzilla.tianocore.org/show_bug.cgi?id=224 > Though I've seen one person talking about how there at least used to be > a bug that means ExitBootServices isn't/wasn't called for one OS. >