[libvirt] [PATCH v5 2/4] qemu: Add PCI-Express root to ARM virt machine

Pavel Fedin p.fedin at samsung.com
Tue Aug 11 11:05:42 UTC 2015


 Hello!

> I liked the idea of adding all this
> if user supplies e.g. <controller type='pci' model='pci-root'/>

 IMHO there would be a usability problem with this:
a) Too much excessive typing.
b) It is not intuitively understood that you have to define the controller explicitly. Especially
because if you run qemu by hands, this is not true. For example, when i first started to cope with
PCI devices, i quickly found out about <address type='pci'> in google. But having to add something
else is not that obvious and easy to discover.
c) AFAIK virt-manager even cannot add PCI controller explicitly, it relies on libvirt's automagic in
question.

 I think it would be a perfect consensus if we add "PCI devices are actually present" to the
condition. In this case, if there is at least one PCI device in the input XML, controller
description is automatically added. If there is none, it's OK to remove it. IMHO it's not difficult
to implement because it's post-parse stage, and everything that the user entered has already been
parsed.
 But we still want the capability check because old qemu versions simply cannot accommodate this.
Therefore it doesn't remove the need to fix up tests.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia





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