From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43935) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YzkVf-0000Ad-H2 for qemu-devel@nongnu.org; Tue, 02 Jun 2015 07:37:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YzkVc-00012L-92 for qemu-devel@nongnu.org; Tue, 02 Jun 2015 07:37:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47954) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YzkVY-00011y-14 for qemu-devel@nongnu.org; Tue, 02 Jun 2015 07:37:28 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id AA774B7CC6 for ; Tue, 2 Jun 2015 11:37:23 +0000 (UTC) Message-ID: <556D9570.5070309@redhat.com> Date: Tue, 02 Jun 2015 14:37:20 +0300 From: Marcel Apfelbaum MIME-Version: 1.0 References: <1432568042-19553-1-git-send-email-marcel@redhat.com> <1432568042-19553-24-git-send-email-marcel@redhat.com> <20150531181221.GJ5268@redhat.com> <556C2985.9000909@redhat.com> <1433158819.19671.23.camel@nilsson.home.kraxel.org> <20150601141532-mutt-send-email-mst@redhat.com> <556C4E3F.7050102@redhat.com> <20150601142731-mutt-send-email-mst@redhat.com> <556C5881.8070605@redhat.com> <556C5E14.6090503@redhat.com> <556C62B7.5080305@redhat.com> <556C7C39.6000201@redhat.com> In-Reply-To: <556C7C39.6000201@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V7 23/24] apci: fix PXB behaviour if used with unsupported BIOS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laszlo Ersek , "Michael S. Tsirkin" Cc: pbonzini@redhat.com, Gerd Hoffmann , qemu-devel@nongnu.org On 06/01/2015 06:37 PM, Laszlo Ersek wrote: > On 06/01/15 15:48, Marcel Apfelbaum wrote: >> On 06/01/2015 04:28 PM, Laszlo Ersek wrote: >>> On 06/01/15 15:05, Marcel Apfelbaum wrote: >>>> On 06/01/2015 03:27 PM, Michael S. Tsirkin wrote: >>>>> On Mon, Jun 01, 2015 at 03:21:19PM +0300, Marcel Apfelbaum wrote: >>>>>> On 06/01/2015 03:17 PM, Michael S. Tsirkin wrote: >>>>>>> On Mon, Jun 01, 2015 at 01:40:19PM +0200, Gerd Hoffmann wrote: >>>>>>>> On Mo, 2015-06-01 at 12:44 +0300, Marcel Apfelbaum wrote: >>>>>>>>> On 05/31/2015 09:12 PM, Michael S. Tsirkin wrote: >>>>>>>>>> On Mon, May 25, 2015 at 06:34:01PM +0300, Marcel Apfelbaum wrote: >>>>>>>>>>> PXB does not work with unsupported bioses, but should >>>>>>>>>>> not interfere with normal OS operation. >>>>>>>>>>> We don't ship them anymore, but it's reasonable >>>>>>>>>>> to keep the work-around until we update the bios in qemu. >>>>>>>>>> >>>>>>>>>> We already did, did we not? >>>>>>>>> Yes, we did, but Gerd preferred to keep this patch around. >>>>>>>>> Adding him to thread. >>>>>>>> >>>>>>>> seabios bundled with qemu isn't the only possible firmware. >>>>>>>> >>>>>>>> We have ovmf, coreboot, qboot. >>>>>>> >>>>>>> ovmf is especially interesting. Marcel, did you look at what >>>>>>> happens with pxb and ovmf? >>>>>> No, I talked to Laszlo about it, he said ovmf is not there yet. >>>>>> OVMF will not query the extra buses, so the devices on the extra bus >>>>>> will not be visible. >>>>>> Adding him to the thread. >>>>>> >>>>>> Thanks, >>>>>> Marcel >>>>> >>>>> But does OVMF need this specific patch? >>>> I don't think so because more than likely it doesn't scan for the extra >>>> buses, >>>> so it will not try to configure these devices. >>>> Laszlo, am I right? >>> >>> Well, I don't know. :) >>> >>> First, I'm not seeing the specific patch in question (can you pls send >>> me a URL into the web archive, or a Message-Id?) >> Well, there are a few patches, all this series, >> You can look for patches: >> 13/24 hw/acpi: add support for i440fx 'snooping' root busses -> acpi >> declarations >> 18/24 hw/pci: introduce PCI Expander Bridge (PXB) >> 19/24 hw/pci: inform bios if the system has extra pci root buses >> >> Basically we add the pxb resources to ACPI tables and then inform BIOS >> using >> etc/extra-pci-roots fw_config file that he has extra roots to scan. >> >> If the OVMF only looks for bus 0 and does not scan all possible buses >> it will not see PXB's root bus > > I don't know enough about PCI to reply sensibly. > > I can tell you that the bus range in OVMF, from "mResAperture" in > "PcAtChipsetPkg/PciHostBridgeDxe/PciHostBridge.c", is [0..0xff], inclusive. > > This bus range is then exposed in the function StartBusEnumeration() to > the caller (which is the PCI bus driver), as an output parameter. The > StartBusEnumeration() function has the following leading comment: > >> Sets up the specified PCI root bridge for the bus enumeration process. >> >> This member function sets up the root bridge for bus enumeration and >> returns the PCI bus range over which the search should be performed >> in ACPI 2.0 resource descriptor format. > > So, there's a chance that if those busses actually exist on the virtual > hardware, the drivers included by OVMF from the generic edk2 source > "will just work". It is also possible that OVMF will notice no change at > all. > > Do you have a public branch, and a matching command line? The PCI > enumeration / resource allocation spews a bunch of messages in OVMF, so > if you placed (on the QEMU command line) some devices on one of these > nonzero buses, then their enumeration / resource allocation, determined > from the log, could serve as evidence. (I think this should be testable > on a non-NUMA host, and without passthrough devices as well.) > > Also, I checked the actual code hunks & message body for this patch (ie. > 23/24) on the web. Looks like I should be able to dump the ACPI tables > in the guest, and get those dumps to you for verification. OVMF does > delay the ACPI download until after PCI enumeration, so the state of the > guest _CRS would be (negative or positive) proof, not lack of proof. Hi Laszlo, I am sorry for the late reply. Can you please check using mst branch? git://git.kernel.org/pub/scm/virt/kvm/mst/qemu.git pxb Just add to the regular command line: -device pxb,id=bridge1,bus_nr=4 -netdev user,id=u -device e1000,id=net2,bus=bridge1,netdev=u,addr=1 Thanks a lot for the help, we mainly want to know if there is an architecture issue that will prevent the PXB to work with OVMF. Marcel > > Thanks > Laszlo > >> Thanks, >> Marcel >> >> >>> Second, recently I tested OVMF on Q35, but not just with a simple / >>> usual command line invocation -- I tested it on a Q35 machine configured >>> by libvirt. That's a very different animal. >>> >>> While it exposed a problem in OVMF's own boot order processing: >>> >>> https://github.com/tianocore/edk2/commit/feca17fa4b >>> >>> I was surprised to see that the PCI bus driver enumerated devices behind >>> two bridges no less without any problems. So, bridges off the one root >>> bridge should work, but several root bridges probably won't. (Exposing >>> root bridges is the responsibility of another driver, and they are not >>> enumerable in the usual way.) >>> >>> Thanks >>> Laszlo >>> >> >