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Re: [libvirt] [PATCH v3 0/9] RISC-V Guest Support



On Wed, 2018-08-22 at 11:15 +0200, Lubomir Rintel wrote:
[...]
>  * Dropped:
>     qemu: no USB by default on RISC-V machines
>     (not sure why I thought this was needed)

I won't hold up the series because of it - in fact I intend to
push it as soon as you have given me feedback for the few trivial
questions I've raised during review - but I think this decision
should be reverted.

I've noticed that the generated command line contains -usb, which
is the legacy syntax for USB support: these days guests are
supposed to use -device instead, hopefully with a virt-friendly
USB controller such as qemu-xhci. All those controllers are PCI,
though, so they won't be usable on RISC-V until the architecture
grows PCI support in QEMU...

Still, we have spent a long time moving away from -usb and I
don't think we should be introducing any more uses of it, so we
should write a follow-up patch that gets rid of that in addition
to getting patch 5/11 from v2 in.

It's not like RISC-V guests would have much use for a USB
controller anyway...

  $ qemu-system-riscv64 -device help 2>&1 | grep -i usb
  name "usb-redir", bus usb-bus
  $

-- 
Andrea Bolognani / Red Hat / Virtualization


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