From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57501) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXWwi-0007t3-Fm for qemu-devel@nongnu.org; Mon, 16 Mar 2015 11:28:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXWwf-0004Yt-3f for qemu-devel@nongnu.org; Mon, 16 Mar 2015 11:28:48 -0400 Date: Mon, 16 Mar 2015 16:28:38 +0100 From: "Michael S. Tsirkin" Message-ID: <20150316162814-mutt-send-email-mst@redhat.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5506C9A8.5050001@redhat.com> 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: Marcel Apfelbaum 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 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? > > > >>> > >>>>+ > >>>>+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