From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34752) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXXFD-0000vD-Co for qemu-devel@nongnu.org; Mon, 16 Mar 2015 11:47:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXXF9-0005Yq-7o for qemu-devel@nongnu.org; Mon, 16 Mar 2015 11:47:55 -0400 Message-ID: <5506FB1E.4060803@redhat.com> Date: Mon, 16 Mar 2015 17:47:42 +0200 From: Marcel Apfelbaum MIME-Version: 1.0 References: <1426001534-7151-1-git-send-email-marcel@redhat.com> <1426001534-7151-29-git-send-email-marcel@redhat.com> <20150310164449-mutt-send-email-mst@redhat.com> <54FF19FA.8040808@redhat.com> <20150310184149-mutt-send-email-mst@redhat.com> <5506C9A8.5050001@redhat.com> <20150316162814-mutt-send-email-mst@redhat.com> In-Reply-To: <20150316162814-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 for-2.3 28/28] docs: Add PXB documentation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: kraxel@redhat.com, quintela@redhat.com, seabios@seabios.org, qemu-devel@nongnu.org, agraf@suse.de, alex.williamson@redhat.com, kevin@koconnor.net, qemu-ppc@nongnu.org, hare@suse.de, imammedo@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, leon.alrae@imgtec.com, aurelien@aurel32.net, rth@twiddle.net On 03/16/2015 05:28 PM, Michael S. Tsirkin wrote: > On Mon, Mar 16, 2015 at 02:16:40PM +0200, Marcel Apfelbaum wrote: >> On 03/10/2015 07:42 PM, Michael S. Tsirkin wrote: >>> On Tue, Mar 10, 2015 at 06:21:14PM +0200, Marcel Apfelbaum wrote: >>>> On 03/10/2015 05:47 PM, Michael S. Tsirkin wrote: >>>>> On Tue, Mar 10, 2015 at 05:32:14PM +0200, Marcel Apfelbaum wrote: >>>>>> Signed-off-by: Marcel Apfelbaum >>>>>> --- >>>>>> docs/pci_expander_bridge.txt | 52 ++++++++++++++++++++++++++++++++++++++++++++ >>>>>> 1 file changed, 52 insertions(+) >>>>>> create mode 100644 docs/pci_expander_bridge.txt >>>>>> >>>>>> diff --git a/docs/pci_expander_bridge.txt b/docs/pci_expander_bridge.txt >>>>>> new file mode 100644 >>>>>> index 0000000..58bf7a8 >>>>>> --- /dev/null >>>>>> +++ b/docs/pci_expander_bridge.txt >>>>>> @@ -0,0 +1,52 @@ >>>>>> +PCI EXPANDER BRIDGE (PXB) >>>>>> +========================= >>>>>> + >>>>>> +Description >>>>>> +=========== >>>>>> +PXB is a "light-weight" host bridge in the same PCI domain >>>>>> +as the main host bridge whose purpose is to enable >>>>>> +the main host bridge to support multiple PCI root buses. >>>>>> +It is implemented only for i440fx. >>>>> >>>>> BTW what makes it i440fx specific? >>>>> Also, what happens if you try to use it >>>>> with a different machine type? >>>> Is is i440fx specific, please look at patch 22/28. >>>> Also we have a specific check for i440fx, so CRS >>>> will not be emitted for other machine types. >>>> >>>> Thanks, >>>> Marcel >>> >>> In fact it won't work at all. Need to think about it, >>> maybe we can make it work more generally. >>> For CRS, should be possible to emit for q35 too? >> We can make it work, but not on the scope of this series. >> However, I'll add a IHostBridgeSnoop interface that will >> make the device work only with associated bus and >> this will make it less general. >> >> Thanks, >> Marcel > > OK, this works too. Do you mean PCIHostBridgeSnoop? Sure. Thanks, Marcel > >>> >>>>> >>>>>> + >>>>>> +As opposed to PCI-2-PCI bridge's secondary bus, PXB's bus >>>>>> +is a primary bus and can be associated with a NUMA node >>>>>> +(different from the main host bridge) allowing the guest OS >>>>>> +to recognize the proximity of a pass-through device to >>>>>> +other resources as RAM and CPUs. >>>>>> + >>>>>> +Usage >>>>>> +===== >>>>>> +A detailed command line would be: >>>>>> + >>>>>> +[qemu-bin + storage options] >>>>>> +-bios [seabios-dir]/out/bios.bin -L [seabios-dir]/out/ >>>>>> +-m 2G >>>>>> +-object memory-backend-ram,size=1024M,policy=bind,host-nodes=0,id=ram-node0 -numa node,nodeid=0,cpus=0,memdev=ram-node0 >>>>>> +-object memory-backend-ram,size=1024M,policy=interleave,host-nodes=0,id=ram-node1 -numa node,nodeid=1,cpus=1,memdev=ram-node1 >>>>>> +-device pxb-device,id=bridge1,bus=pci.0,numa_node=1,bus_nr=4 -netdev user,id=nd-device e1000,bus=bridge1,addr=0x4,netdev=nd >>>>>> +-device pxb-device,id=bridge2,bus=pci.0,numa_node=0,bus_nr=8 -device e1000,bus=bridge2,addr=0x3 >>>>>> +-device pxb-device,id=bridge3,bus=pci.0,bus_nr=40 -drive if=none,id=drive0,file=[img] -device virtio-blk-pci,drive=drive0,scsi=off,bus=bridge3,addr=1 >>>>>> + >>>>>> +Here you have: >>>>>> + - 2 NUMA nodes for the guest, 0 and 1. (both mapped to the same NUMA node in host, but you can and should put it in different host NUMA nodes) >>>>>> + - a pxb host bridge attached to NUMA 1 with an e1000 behind it >>>>>> + - a pxb host bridge attached to NUMA 0 with an e1000 behind it >>>>>> + - a pxb host bridge not attached to any NUMA with a hard drive behind it. >>>>>> + >>>>>> +Implementation >>>>>> +============== >>>>>> +The PXB is composed by: >>>>>> +- HostBridge (TYPE_PXB_HOST) >>>>>> + The host bridge allows to register and query the PXB's rPCI root bus in QEMU. >>>>>> +- PXBDev(TYPE_PXB_DEVICE) >>>>>> + It is a regular PCI Device that resides on the piix host-bridge bus and its bus uses the same PCI domain. >>>>>> + However, the bus behind is exposed through ACPI as a primary PCI bus and starts a new PCI hierarchy. >>>>>> + The interrupts from devices behind the PXB are routed through this device the same as if it were a >>>>>> + PCI-2-PCI bridge. The _PRT follows the i440fx model. >>>>>> +- PCIBridgeDev(TYPE_PCI_BRIDGE_DEV) >>>>>> + Created automatically as part of init sequence. >>>>>> + When adding a device to PXB it is attached to the bridge for two reasons: >>>>>> + - Using the bridge will enable hotplug support >>>>>> + - All the devices behind the bridge will use bridge's IO/MEM windows compacting >>>>>> + the PCI address space. >>>>>> + >>>>>> -- >>>>>> 2.1.0