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Frediano Ziglio
14694975cd
Describe the usage of devices 5853:0002 and 5853:C000. Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com> Reviewed-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
97 lines
3.2 KiB
INI
97 lines
3.2 KiB
INI
=head1 NAME
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xen-pci-device-reservations - Xen PCI device ID registry
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=head1 Description
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PCI vendor ID 0x5853 has been reserved for use by Xen systems in order to
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advertise certain virtual hardware to guest virtual machines. The primary
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use of this is with device ID 0x0001 to advertise the Xen Platform PCI
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device - the presence of this virtual device enables a guest Operating
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System (subject to the availability of suitable drivers) to make use of
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paravirtualisation features such as disk and network devices etc.
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XenServer, for Windows machines, may present Xen Platform device with device
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ID 0x0002 instead of 0x0001. Device 0x0001 and 0x0002 should be mutually
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exclusive.
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Some Xen vendors wish to provide alternative and/or additional guest drivers
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that can bind to virtual devices[1]. This may be done using the Xen PCI
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vendor ID of 0x5853 and Xen-vendor/device specific PCI device IDs. This file
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records reservations made within the device ID range in order to avoid
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multiple Xen vendors using conflicting IDs.
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=head1 Guidelines
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=over 4
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=item 1. A vendor may request a range of device IDs by submitting a patch to
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this file.
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=item 2. Vendor allocations should be in the range 0xc000-0xfffe to reduce the
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possibility of clashes with community IDs assigned from the bottom up.
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=item 3. The vendor is responsible for allocations within the range and should
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try to record specific device IDs in PCI ID databases such as
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https://pci-ids.ucw.cz and https://devicehunt.com
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=back
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=head1 Reservations
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range | vendor/product
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--------------+--------------------------------------------------------------
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0x0001 | (Xen Platform PCI device)
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0x0002 | Citrix XenServer (grandfathered allocation for XenServer 6.1)
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0xc000-0xc0ff | Citrix XenServer
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0xc100-0xc1ff | Citrix XenClient
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0xc200-0xc2ff | XCP-ng Project (https://xcp-ng.org)
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=head1 Notes
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=over 4
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=item 1.
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Upstream QEMU provides a parameterized device called xen-pvdevice that
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can be used to host guest drivers. Execute:
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qemu-system-i386 -device xen-pvdevice,help
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for a list of all parameters. The following parameters are relevant to
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driver binding:
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=over 4
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=item vendor-id (default 0x5853)
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The PCI vendor ID and subsystem vendor ID of the device.
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=item device-id (must be specified)
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The PCI device ID and subsystem device ID of the device.
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=item revision (default 0x01)
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The PCI revision of the device
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=back
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Also the size parameter (default 0x400000) can be used to specify the
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size of the single MMIO BAR that the device exposes. This area may be
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used by drivers for mapping grant tables, etc.
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Note that the presence of the Xen Platform PCI device is generally a
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pre-requisite for an additional xen-pvdevice as it is the platform
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device that provides that IO ports necessary for unplugging emulated
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devices. See hvm-emulated-unplug.markdown for details of the IO ports
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and unplug protocol.
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libxl provides support for creation of a single additional xen-pvdevice.
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See the vendor_device parameter in xl.cfg(5).
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XenServer might present a xen-pvdevice device with ID 0xC000.
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Such device is a placeholder for Windows update usage and is always exposed
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in conjunction with a Xen Platform PCI device, usually with ID 0x0002
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=back
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