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[Qemu-devel] [PATCH V8 17/17] docs: Add PXB documentation
From: |
Marcel Apfelbaum |
Subject: |
[Qemu-devel] [PATCH V8 17/17] docs: Add PXB documentation |
Date: |
Tue, 2 Jun 2015 14:23:12 +0300 |
Signed-off-by: Marcel Apfelbaum <address@hidden>
---
docs/pci_expander_bridge.txt | 58 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 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..d7913fb
--- /dev/null
+++ b/docs/pci_expander_bridge.txt
@@ -0,0 +1,58 @@
+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 and can be placed only
+on bus 0 (pci.0).
+
+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]
+-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=bind,host-nodes=1,id=ram-node1
-numa node,nodeid=1,cpus=1,memdev=ram-node1
+-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
+-device pxb,id=bridge2,bus=pci.0,numa_node=0,bus_nr=8,bus=pci.0 -device
e1000,bus=bridge2,addr=0x3
+-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
+
+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.
+
+Limitations
+===========
+Please observe that we specified the bus "pci.0" for the second and third pxb.
+This is because when no bus is given, another pxb can be selected by QEMU as
default bus,
+however, PXBs can be placed only under the root bus.
+
+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
- [Qemu-devel] [PATCH V8 07/17] hw/apci: add _PRT method for extra PCI root busses, (continued)
- [Qemu-devel] [PATCH V8 07/17] hw/apci: add _PRT method for extra PCI root busses, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 08/17] hw/acpi: add _CRS method for extra root busses, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 10/17] hw/pci: removed 'rootbus nr is 0' assumption from qmp_pci_query, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 09/17] hw/acpi: remove from root bus 0 the crs resources used by other buses., Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 12/17] hw/pci: inform bios if the system has extra pci root buses, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 13/17] hw/pxb: add map_irq func, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 11/17] hw/pci: introduce PCI Expander Bridge (PXB), Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 14/17] hw/pci: add support for NUMA nodes, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 15/17] hw/pxb: add numa_node parameter, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 16/17] apci: fix PXB behaviour if used with unsupported BIOS, Marcel Apfelbaum, 2015/06/02
- [Qemu-devel] [PATCH V8 17/17] docs: Add PXB documentation,
Marcel Apfelbaum <=
- Re: [Qemu-devel] [PATCH V8 00/17] hw/pc: implement multiple primary busses for pc machines, Laszlo Ersek, 2015/06/03