xen-pci-device-reservations - Xen PCI device ID registry
PCI vendor ID 0x5853 has been reserved for use by Xen systems in order to
advertise certain virtual hardware to guest virtual machines. The primary use
of this is with device ID 0x0001 to advertise the Xen Platform PCI device -
the presence of this virtual device enables a guest Operating System (subject
to the availability of suitable drivers) to make use of paravirtualisation
features such as disk and network devices etc.
Some Xen vendors wish to provide alternative and/or additional
guest drivers that can bind to virtual devices. This may be done using
the Xen PCI vendor ID of 0x5853 and Xen-vendor/device specific PCI device
IDs. This file records reservations made within the device ID range in order
to avoid multiple Xen vendors using conflicting IDs.
- 1. A vendor may request a range of device IDs by submitting a patch to
- 2. Vendor allocations should be in the range 0xc000-0xfffe to reduce the
possibility of clashes with community IDs assigned from the bottom up.
- 3. The vendor is responsible for allocations within the range and should
try to record specific device IDs in PCI ID databases such as
https://pci-ids.ucw.cz and https://devicehunt.com
range | vendor/product
0x0001 | (Xen Platform PCI device)
0x0002 | Citrix XenServer (grandfathered allocation for XenServer 6.1)
0xc000-0xc0ff | Citrix XenServer
0xc100-0xc1ff | Citrix XenClient
0xc200-0xc2ff | XCP-ng Project (https://xcp-ng.org)
- Upstream QEMU provides a parameterized device called xen-pvdevice that can
be used to host guest drivers. Execute:
qemu-system-i386 -device xen-pvdevice,help
for a list of all parameters. The following parameters are
relevant to driver binding:
- vendor-id (default 0x5853)
- The PCI vendor ID and subsystem vendor ID of the device.
- device-id (must be specified)
- The PCI device ID and subsystem device ID of the device.
- revision (default 0x01)
- The PCI revision of the device
Also the size parameter (default 0x400000) can be used to specify
the size of the single MMIO BAR that the device exposes. This area may be
used by drivers for mapping grant tables, etc.
Note that the presence of the Xen Platform PCI device is generally
a pre-requisite for an additional xen-pvdevice as it is the platform device
that provides that IO ports necessary for unplugging emulated devices. See
hvm-emulated-unplug.markdown for details of the IO ports and unplug
libxl provides support for creation of a single additional
xen-pvdevice. See the vendor_device parameter in xl.cfg(5).