From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:49265) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UCSrQ-0007VO-Ng for qemu-devel@nongnu.org; Mon, 04 Mar 2013 05:43:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UCSrP-0007mt-G4 for qemu-devel@nongnu.org; Mon, 04 Mar 2013 05:43:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:14943) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UCSrP-0007mL-4Z for qemu-devel@nongnu.org; Mon, 04 Mar 2013 05:43:11 -0500 Date: Mon, 4 Mar 2013 12:43:01 +0200 From: Gleb Natapov Message-ID: <20130304104301.GL23616@redhat.com> References: <20130303091738.GB23616@redhat.com> <513471F1.5020702@redhat.com> <20130304102131.GK23616@redhat.com> <51347735.9090204@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51347735.9090204@redhat.com> Subject: Re: [Qemu-devel] [PATCH v13 0/8] pv event interface between host and guest List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Peter Maydell , kvm list , "Michael S. Tsirkin" , Hu Tao , qemu-devel , Markus Armbruster , Blue Swirl , Orit Wasserman , Juan Quintela , Alexander Graf , Jan Kiszka , Andrew Jones , Alex Williamson , Sasha Levin , Stefan Hajnoczi , Luiz Capitulino , KAMEZAWA Hiroyuki , Kevin Wolf , Anthony Liguori , Marcelo Tosatti , "linux-kernel@vger.kernel.org" On Mon, Mar 04, 2013 at 11:28:05AM +0100, Paolo Bonzini wrote: > Il 04/03/2013 11:21, Gleb Natapov ha scritto: > >> > Just to clarify it for Hu Tao, the read from a random ioport is how the > >> > ACPI code will detect presence of the device. > >> > > > Actually no (at least in the long run, for the first version it may be > > OK). > > Agreed. > > > Since we want to move DSDT generation into QEMU if device will not > > be present QEMU will not generate corresponded Device() in DSDT, or it > > will generate it with _STA() { Return (0x00)} hard coded. > > Yes, this would be good. > > > Seabios can do > > the same if we will pass it info about device presence via fw_cfg. > > True, but I don't like this a lot. I don't like splitting decisions > between SeaBIOS and the DSDT, you end up touching code all over the > place and writing ASL is simpler than patching---even with all the > machinery that we have. That's the main argument in favor of moving DSDT into QEMU regardless of this patch series, but as long as we have it in Seabios, have infrastructure for patching and use it for many things already I do not see why avoiding it. > It is also simpler to move ASL from SeaBIOS to > OVMF and/or viceversa. I don't recall what was the opposition to a > fw_cfg driver directly in the DSDT, but I think this would be a good > usage for it. > Basically fw_cfg was not designed with this in mind. It was really meant to be simple interface for FW running one one CPU to use. You probably may do locking with AML too to guaranty atomic access, but things get complicated. Also may option that was added lately use file interface (since this is what Kevin prefers) and manipulating strings in AML is probably not what we want. > Splitting it between QEMU and DSDT is a bit better, since you have to > touch QEMU anyway to implement the feature. > > Anyhow, this does not apply to the next submission of this series. I > think we can agree to the compromise of using ACPI but still read the > port in _STA. > If you want to make ioport configurable I do not see how can we avoid patching. -- Gleb.