[Xen-devel] [RFC] Use device path to assign devices to guest domain

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

I'm considering making a patch to use device path to assign devices to
guest domain.

We can reserve devices which will be assigned to guest domain by using
devicepath in boot parameter of dom0.
 ex)
  guestdev=PNP0A08:0-0.0,PNP0A08:0-2.0

But we can't use device path in the guest configuration file now.

To enable it, I will add the following functions.

 - Add "devicepath" and "assignable" field to PPCI class.

 - Use device path, vender ID and device ID to decide uuid value of
   PPCI class.

    Now uuid value of PPCI class is decided by SBDF only. SBDF of
    particular slot can be changed. So uuid value of particular PPCI
    class is changed too if SBDF is changed.
    On the other hand, device path of that isn't changed. So we can use
    device path to decide whether uuid value of particular PPCI class
    should be changed or not.

    But there is a problem with using device path only. If the device
    of particular slot is exchanged for another device, uuid value
    isn't changed. In this case, uuid value should be changed. So
    vender ID and device ID are necessary for recognition of exchange
    of device.

 - Enable device path in pci parameter of guest configuration file.
   The format is below.
    pci=['device path' or 'SBDF', ...]

    ex)
     pci=['PNP0A08:0-2.0-0.0', 'PNP0A08:0-4.0-0.0']
      or
     pci=['0000:00:1.0', '0000:00:2.0']

I hope developers give me some comments.

Thanks,
--
Yuji Shimada


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