From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Greaves Subject: Re: [PATCH 000 of 5] md: Introduction Date: Sat, 21 Jan 2006 00:42:03 +0000 Message-ID: <43D1835B.1040105@dgreaves.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Andre' Breiler , neilb@suse.de Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Andre' Breiler wrote: >Hi, > >On Fri, 20 Jan 2006, Reuben Farrelly wrote: > > >>On 20/01/2006 11:32 a.m., Neil Brown wrote: >> >> >>>The in-kernel autodetection in md is purely legacy support as far as I >>>am concerned. md does volume detection in user space via 'mdadm'. >>> >>> >>Hrm. How would I then start my md0 raid-1 array that is >>mounted as the root partition / if I'm not doing this when the kernel is >>starting up? Because without it I've got no userspace to actually execute. >> >> > >Indeed you won't be able to use a 'plain kernel' anymore but switch to >kernel + initrd. > > I understand the anti-autodetect arguments and was easily persuaded by them... Can I however suggest we have autodetect only actually triggers if the kernel is supplied with the UUID of an md0 as a boot option. ie: root=/dev/md0 md0=b87a211e:8a9bef34:ccc334d8:f84216d6 I'm not sure I ever saw this proposed during the debate. It's just *so* nice not to have to bother with initrd (having just moved to a mirrored root and finding it wonderfully easy to specify root=/dev/md0 and have it 'just work') It looks easy enough to add into autorun_devices() in md.c Maybe then deprecate autodetect more quickly by having it optional in 2.6.17(?) - but if even one UUID *is* specified then no other devices are autodetected. Eventually having no devices autodetected *unless* a UUID is specified (for convenience printk the UUIDs of devices that *are* found just in case you mistype it...) Please forgive me if I've missed the reason that this is a bad idea. David --