From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43815) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vpx4k-0005ip-M4 for qemu-devel@nongnu.org; Mon, 09 Dec 2013 04:24:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vpx4f-0002QK-T5 for qemu-devel@nongnu.org; Mon, 09 Dec 2013 04:24:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54219) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vpx4f-0002QG-Ix for qemu-devel@nongnu.org; Mon, 09 Dec 2013 04:24:21 -0500 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id rB99OKwp008282 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 9 Dec 2013 04:24:20 -0500 Message-ID: <1386581052.10879.22.camel@localhost.localdomain> From: Marcel Apfelbaum Date: Mon, 09 Dec 2013 11:24:12 +0200 In-Reply-To: <1386573270.8684.11.camel@nilsson.home.kraxel.org> References: <1386329080-28836-1-git-send-email-kraxel@redhat.com> <20131208113138.GC6841@redhat.com> <1386573270.8684.11.camel@nilsson.home.kraxel.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] pci: fix pci bridge fw path List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" On Mon, 2013-12-09 at 08:14 +0100, Gerd Hoffmann wrote: > On So, 2013-12-08 at 13:31 +0200, Michael S. Tsirkin wrote: > > On Fri, Dec 06, 2013 at 12:24:40PM +0100, Gerd Hoffmann wrote: > > > qemu uses "pci" as name for pci bridges in the firmware device path. > > > seabios expects "pci-bridge". Result is that bootorder is broken for > > > devices behind pci bridges. > > > > > > Some googling suggests that "pci-bridge" is the correct one. At least > > > PPC-based Apple machines are using this. See question "How do I boot > > > from a device attached to a PCI card" here: > > > http://www.netbsd.org/ports/macppc/faq.html > > > > > > So lets change qemu to use "pci-bridge" too. > > > > > > Signed-off-by: Gerd Hoffmann > > > > Sounds good but this needs to be enabled for > > new machine types only - otherwise guest will read > > corrupted data since bootindex is in FW CFG. > > Come on, that is seriously over-engineering. Does this change affects migration in any way? > > First, the chance that you'll find setup in the field where this can > actually happen in practice is very low as bootorder for devices behind > pci bridges does not work at all without this patch. > > Second, the race window is so tiny that nobody has ever seen that happen > in testing. > > > Alternatively, extend > > 04920fc0faa4760f9c4fc0e73b992b768099be70 > > to work for all fw cfg file entries. > > > > I think the whole boot index thing needs > > to be reworked: we also have the long-standing feature request to allow > > booting from a device added by hot add. > > I'm not going to rewrite bootorder just to get a one-liner bugfix > merged. Why? You could rewrite Qemu in C++, then rewrite the bootorder (easier, because of C++) and finally get your bugfix in... but again, your patch would look exactly the same :) Thanks, Marcel > > cheers, > Gerd > >