From: Peter Krempa <pkrempa@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: libvir-list@redhat.com, qemu-devel@nongnu.org
Subject: Re: device hotplug & file handles
Date: Thu, 7 May 2020 18:18:57 +0200 [thread overview]
Message-ID: <20200507161857.GK2102825@angien.pipo.sk> (raw)
In-Reply-To: <20200507144914.4zg3753uh3kytz6g@sirius.home.kraxel.org>
On Thu, May 07, 2020 at 16:49:14 +0200, Gerd Hoffmann wrote:
> Hi,
>
> For usb device pass-through (aka -device usb-host) it would be very
> useful to pass file handles from libvirt to qemu. The workflow would
> change from ...
>
> (1) libvirt enables access to /dev/usb/$bus/$dev
> (2) libvirt passes $bus + $dev (using hostbus + hostaddr properties)
> to qemu.
> (3) qemu opens /dev/usb/$bus/$dev
>
> ... to ...
>
> (1) libvirt opens /dev/usb/$bus/$dev
> (2) libvirt passes filehandle to qemu.
>
> Question is how can we pass the file descriptor best? My idea would be
> to simply add an fd property to usb-host:
>
> * Coldplug would be "-device usb-host,fd=<nr>" (cmd line).
> * Hotplug would be "device_add usb-host,fd=<getfd-name>" (monitor).
We have prior art for both approaches so it's fine.
>
> Will that work from libvirt point of view?
Sure! Just please make sure that the new approach is detectable somehow.
Either via device-list-properties or query-qmp-schema.
> Or does anyone have an better idea?
>
> thanks,
> Gerd
>
> PS: background: https://bugzilla.redhat.com/show_bug.cgi?id=1595525
>
next prev parent reply other threads:[~2020-05-07 16:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 14:49 device hotplug & file handles Gerd Hoffmann
2020-05-07 16:18 ` Peter Krempa [this message]
2020-05-07 17:05 ` Eric Blake
2020-05-11 10:20 ` Michal Privoznik
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