From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:56282) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R33eU-0005ZX-TI for qemu-devel@nongnu.org; Mon, 12 Sep 2011 06:22:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1R33eT-0001KA-N3 for qemu-devel@nongnu.org; Mon, 12 Sep 2011 06:22:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2081) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1R33eT-0001K3-D8 for qemu-devel@nongnu.org; Mon, 12 Sep 2011 06:22:09 -0400 Date: Mon, 12 Sep 2011 07:21:48 -0300 From: Marcelo Tosatti Message-ID: <20110912102148.GA12332@amt.cnet> References: <1749303074.590739.1315551830460.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> <1466280941.590770.1315552101666.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> <20110909073226.GB5593@redhat.com> <1315587902.2662.19.camel@x201.home> <20110909183426.GD22662@amt.cnet> <20110911092357.GC27096@redhat.com> <20110911150149.GA28477@amt.cnet> <20110911185106.GA4740@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110911185106.GA4740@redhat.com> Subject: Re: [Qemu-devel] About hotplug multifunction List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org, blauwirbel@gmail.com, yamahata@valinux.co.jp, Alex Williamson , Amos Kong On Sun, Sep 11, 2011 at 09:51:06PM +0300, Michael S. Tsirkin wrote: > On Sun, Sep 11, 2011 at 12:01:49PM -0300, Marcelo Tosatti wrote: > > On Sun, Sep 11, 2011 at 12:23:57PM +0300, Michael S. Tsirkin wrote: > > > On Fri, Sep 09, 2011 at 03:34:26PM -0300, Marcelo Tosatti wrote: > > > > > > something I noted when readin our acpi code: > > > > > > we currently pass eject request for function 0 only: > > > > > > Name (_ADR, nr##0000) > > > > > > We either need a device per function there (acpi 1.0), > > > > > > send eject request for them all, or use ffff > > > > > > as function number (newer acpi, not sure which version). > > > > > > Need to see which guests (windows,linux) can handle which form. > > > > > > > > > > I'd guess we need to change that to ffff. > > > > > > > > No need, only make sure function 0 is there and all other functions > > > > should be removed automatically by the guest on eject notification. > > > > > > Hmm, the ACPI spec explicitly says: > > > > > > High word = Device #, Low word = Function #. > > > (e.g., device 3, function 2 is 0x00030002). To refer > > > to all the functions on a device #, use a function > > > number of FFFF). > > > > Right, but this is the _ADR of the device instance in ACPI. > > The communication between QEMU and the ACPI DSL code is all > > based in slots. > > It's easy to extend that if we like though. > > > > > ACPI PCI hotplug is based on slots, not on functions. It does not > > > > support addition/removal of individual functions. > > > > > > Interesting. Is this just based on general logic, > > > reading of the linux driver or the ACPI spec? > > > > Its based on Seabios ACPI DST implementation and its relationship with > > the QEMU implementation in acpi_piix4.c. > > > > > The ACPI spec itself seems pretty vague. All tables > > > list devices, where each device has an _ADR entry, > > > which is built up of PCI device # and function #. > > > > Yes, it is vague. Given the mandate from the PCI spec a device _must > > contain_ function 0, usage (including hotplug/unplug) of individual > > functions other than 0 as separate devices is a no-go. > > It doesn't seem to be a big issue. > We could, for example, keep a stub function 0 around. I suppose the guest will remove all functions of a device once you attempt to hot-unplug a function. What is the problem with adding more PCI buses, instead of multifunction ?