From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59685) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOI0m-0006N6-J7 for qemu-devel@nongnu.org; Tue, 16 Oct 2012 21:01:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TOI0l-0003y5-9S for qemu-devel@nongnu.org; Tue, 16 Oct 2012 21:01:28 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:33551) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TOI0k-0003xk-P2 for qemu-devel@nongnu.org; Tue, 16 Oct 2012 21:01:27 -0400 Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 17 Oct 2012 10:58:21 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q9H0pORE48824476 for ; Wed, 17 Oct 2012 11:51:24 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q9H11MvW001211 for ; Wed, 17 Oct 2012 12:01:22 +1100 Date: Wed, 17 Oct 2012 12:01:07 +1100 From: David Gibson Message-ID: <20121017010107.GZ4640@truffula.fritz.box> References: <87wqyqyyxi.fsf@codemonkey.ws> <874nluqaeh.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874nluqaeh.fsf@codemonkey.ws> Subject: Re: [Qemu-devel] nvram and boot order List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Peter Maydell , Avik Sil , qemu-devel@nongnu.org, Alex Graf On Tue, Oct 16, 2012 at 06:12:22PM -0500, Anthony Liguori wrote: > Peter Maydell writes: > > > On 16 October 2012 20:55, Anthony Liguori wrote: > >> > >> We discussed nvram and it's interaction with boot order in today's KVM > >> call. Here's the outcome. This list is completely incremental so it's > >> fine to start with 1-4, for instance, as long as we eventually get to 6. > >> > >> Today, on x86, we implement up to (5) but we don't persist NVRAM. > >> > >> 1) We should modify QEMUMachine to specify that a machine does not want > >> a default boot order. Ideally, this would be done by adding a new > >> default_boot_order that is set to "cad" explicitly in all machines > >> allowing a machine to remove that entry. At any rate, this allows a > >> machine to receive a NULL boot order when -boot isn't used and take an > >> appropriate action accordingly. > >> > >> 2) In the absence of a persistent NVRAM, a ephemeral NVRAM should be > >> generated with a reasonable default boot order. > >> > >> 3) In the absence of -boot or ,bootindex=, the system should boot from > >> order specified in NVRAM. > >> > >> 4) If -boot is specified, the parameter should alter the contents of > >> NVRAM to change the boot order to what is specified by -boot. > >> > >> 5) If ,bootorder is specified, it should take predence over -boot. > >> > >> 6) ,bootorder= should also alter the contents of NVRAM to determine the > >> boot order. > > > > What's the rationale for 6? It seems a bit odd for a command line > > option to randomly mangle the NVRAM... > > The use case is to have a consistent view of the boot order within the > guest and in the host while still having the ability to edit the > persistent boot order within the guest. > > If you look at my other note in this thread, one way to achieve this is > to have the boot order "owned" by QEMU with the guest making fw_cfg > calls to modify it. It would be persisted in a portion of the NVRAM > reserved for QEMU's use. That's not necessarily compatible with established guest visible platform NVRAM semantics. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson