Re: [PATCH 0/4] USB hostdev: allow addressing by port
On Mon, Apr 21, 2025 at 09:38:34PM +0200, Maximilian Martin via Devel wrote:
This resubmission splits up the previous patch into multiple patches
and
incorporates review comments from Michal Prívozník.
Currently, only vendor/product and bus/device matching are supported for USB host
devices. Neither of these provide a stable and persistent way of assigning a guest
a specific host device. Vendor/product can be ambiguous. Device numbers change on
every enumeration.
This patch adds a bus/port matching, which allows a specific port on the host to be
specified using the dotted notation found in Linux's "devpath" sysfs
attribute.
In terms of our API, we're expecting people to use the
'node device' APIs to identify what devices are available
on the host and their attributes, rather than queryin
Linux directly. This gives us a platform independant
usage model, which also works when the mgmt app has no
login to the virt host.
Currently for USB devices we report bus, dev, vendor & product,
but don't report the port:
# virsh nodedev-dumpxml usb_1_10_4
<device>
<name>usb_1_10_4</name>
<path>/sys/devices/pci0000:00/0000:00:14.0/usb1/1-10/1-10.4</path>
<devnode type='dev'>/dev/bus/usb/001/004</devnode>
<parent>usb_1_10</parent>
<driver>
<name>usb</name>
</driver>
<capability type='usb_device'>
<bus>1</bus>
<device>4</device>
<product id='0x10c0'>Dell Integrated Hub</product>
<vendor id='0x1604'>Tascam</vendor>
</capability>
</device>
we need to add 'port' to this xml document under the 'usb_device'
capability.
With regards,
Daniel
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