|
 |
8be556 |
From 5bbadf30a3ac2651b67b71aa105fe3f854e4d2ef Mon Sep 17 00:00:00 2001
|
|
|
8be556 |
From: Marcel Apfelbaum <marcel@redhat.com>
|
|
|
8be556 |
Date: Wed, 24 Jun 2015 13:53:36 +0200
|
|
|
8be556 |
Subject: [PATCH 213/217] docs: Add PXB documentation
|
|
|
8be556 |
|
|
|
8be556 |
Message-id: <1435154016-26233-44-git-send-email-marcel@redhat.com>
|
|
|
8be556 |
Patchwork-id: 66470
|
|
|
8be556 |
O-Subject: [RHEL-7.2 qemu-kvm-rhev PATCH 43/43] docs: Add PXB documentation
|
|
|
8be556 |
Bugzilla: 1103313
|
|
|
8be556 |
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
|
|
|
8be556 |
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
8be556 |
RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
|
|
|
8be556 |
|
|
|
8be556 |
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
|
|
|
8be556 |
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
8be556 |
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
|
|
|
8be556 |
Acked-by: Laszlo Ersek <lersek@redhat.com>
|
|
|
8be556 |
(cherry picked from commit 814550d73a94dcf9f2c9f8d2ee280226f1145388)
|
|
|
8be556 |
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
|
|
|
8be556 |
---
|
|
|
8be556 |
docs/pci_expander_bridge.txt | 58 ++++++++++++++++++++++++++++++++++++++++++++
|
|
|
8be556 |
1 file changed, 58 insertions(+)
|
|
|
8be556 |
create mode 100644 docs/pci_expander_bridge.txt
|
|
|
8be556 |
|
|
|
8be556 |
diff --git a/docs/pci_expander_bridge.txt b/docs/pci_expander_bridge.txt
|
|
|
8be556 |
new file mode 100644
|
|
|
8be556 |
index 0000000..d7913fb
|
|
|
8be556 |
--- /dev/null
|
|
|
8be556 |
+++ b/docs/pci_expander_bridge.txt
|
|
|
8be556 |
@@ -0,0 +1,58 @@
|
|
|
8be556 |
+PCI EXPANDER BRIDGE (PXB)
|
|
|
8be556 |
+=========================
|
|
|
8be556 |
+
|
|
|
8be556 |
+Description
|
|
|
8be556 |
+===========
|
|
|
8be556 |
+PXB is a "light-weight" host bridge in the same PCI domain
|
|
|
8be556 |
+as the main host bridge whose purpose is to enable
|
|
|
8be556 |
+the main host bridge to support multiple PCI root buses.
|
|
|
8be556 |
+It is implemented only for i440fx and can be placed only
|
|
|
8be556 |
+on bus 0 (pci.0).
|
|
|
8be556 |
+
|
|
|
8be556 |
+As opposed to PCI-2-PCI bridge's secondary bus, PXB's bus
|
|
|
8be556 |
+is a primary bus and can be associated with a NUMA node
|
|
|
8be556 |
+(different from the main host bridge) allowing the guest OS
|
|
|
8be556 |
+to recognize the proximity of a pass-through device to
|
|
|
8be556 |
+other resources as RAM and CPUs.
|
|
|
8be556 |
+
|
|
|
8be556 |
+Usage
|
|
|
8be556 |
+=====
|
|
|
8be556 |
+A detailed command line would be:
|
|
|
8be556 |
+
|
|
|
8be556 |
+[qemu-bin + storage options]
|
|
|
8be556 |
+-m 2G
|
|
|
8be556 |
+-object memory-backend-ram,size=1024M,policy=bind,host-nodes=0,id=ram-node0 -numa node,nodeid=0,cpus=0,memdev=ram-node0
|
|
|
8be556 |
+-object memory-backend-ram,size=1024M,policy=bind,host-nodes=1,id=ram-node1 -numa node,nodeid=1,cpus=1,memdev=ram-node1
|
|
|
8be556 |
+-device pxb,id=bridge1,bus=pci.0,numa_node=1,bus_nr=4 -netdev user,id=nd-device e1000,bus=bridge1,addr=0x4,netdev=nd
|
|
|
8be556 |
+-device pxb,id=bridge2,bus=pci.0,numa_node=0,bus_nr=8,bus=pci.0 -device e1000,bus=bridge2,addr=0x3
|
|
|
8be556 |
+-device pxb,id=bridge3,bus=pci.0,bus_nr=40,bus=pci.0 -drive if=none,id=drive0,file=[img] -device virtio-blk-pci,drive=drive0,scsi=off,bus=bridge3,addr=1
|
|
|
8be556 |
+
|
|
|
8be556 |
+Here you have:
|
|
|
8be556 |
+ - 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)
|
|
|
8be556 |
+ - a pxb host bridge attached to NUMA 1 with an e1000 behind it
|
|
|
8be556 |
+ - a pxb host bridge attached to NUMA 0 with an e1000 behind it
|
|
|
8be556 |
+ - a pxb host bridge not attached to any NUMA with a hard drive behind it.
|
|
|
8be556 |
+
|
|
|
8be556 |
+Limitations
|
|
|
8be556 |
+===========
|
|
|
8be556 |
+Please observe that we specified the bus "pci.0" for the second and third pxb.
|
|
|
8be556 |
+This is because when no bus is given, another pxb can be selected by QEMU as default bus,
|
|
|
8be556 |
+however, PXBs can be placed only under the root bus.
|
|
|
8be556 |
+
|
|
|
8be556 |
+Implementation
|
|
|
8be556 |
+==============
|
|
|
8be556 |
+The PXB is composed by:
|
|
|
8be556 |
+- HostBridge (TYPE_PXB_HOST)
|
|
|
8be556 |
+ The host bridge allows to register and query the PXB's rPCI root bus in QEMU.
|
|
|
8be556 |
+- PXBDev(TYPE_PXB_DEVICE)
|
|
|
8be556 |
+ It is a regular PCI Device that resides on the piix host-bridge bus and its bus uses the same PCI domain.
|
|
|
8be556 |
+ However, the bus behind is exposed through ACPI as a primary PCI bus and starts a new PCI hierarchy.
|
|
|
8be556 |
+ The interrupts from devices behind the PXB are routed through this device the same as if it were a
|
|
|
8be556 |
+ PCI-2-PCI bridge. The _PRT follows the i440fx model.
|
|
|
8be556 |
+- PCIBridgeDev(TYPE_PCI_BRIDGE_DEV)
|
|
|
8be556 |
+ Created automatically as part of init sequence.
|
|
|
8be556 |
+ When adding a device to PXB it is attached to the bridge for two reasons:
|
|
|
8be556 |
+ - Using the bridge will enable hotplug support
|
|
|
8be556 |
+ - All the devices behind the bridge will use bridge's IO/MEM windows compacting
|
|
|
8be556 |
+ the PCI address space.
|
|
|
8be556 |
+
|
|
|
8be556 |
--
|
|
|
8be556 |
1.8.3.1
|
|
|
8be556 |
|