Re: [Qemu-devel] virtio-input questions

[Jiri 'Ghormoon' Novak]

Hi,

resending this, seems you did a typo when CCing qemu-devel and I've just 
blindly replied-all and got a bounce, sorry for doubled mail, I keep you 
both in recipients so we don't have multiple threads later.

Gh.

Jiri 'Ghormoon' Novak wrote:
> Hi
>
> Gerd Hoffmann wrote:
> >    Hi,
> >
> > [ Cc'ing qemu-devel + alex ]
> >
> > > when discussing my attempts at passthrough of ps2 input, I've been
> > > pointed towards your work on virtio-input.
> > > I've got a question:
> > > Did you think about attaching those to standard qemu input, so even
> > > hosts without virtio drivers can use them? It would be great help if
> > > keyboard could be used like that.
> > You mean grab events from /dev/input/event$nr and feed them into the
> > qemu input system, so they show up on whatever emulated input device the
> > guest happens to have?  Should be doable for keyboard and mouse.  Not so
> > easy for tablet/touchscreen.
> >
> > Might be useful for people doing vga pass-through using vfio too,
> > keyboard/mouse input is a constant source of trouble there.
> Exactly that's my use-case. I'm doing VGA-passthrough of my only 
> (laptop) VGA and passing in the laptop keyboard too (they're still ps2 
> keyboards technically, not usb, that would be fairly easy).
>
> I'm curretly using a hack that I got here: 
> http://lists.xen.org/archives/html/xen-devel/2010-03/msg01292.html and 
> heavily modified it for qemu 2. But I've done it very wrong back then 
> - hacking pckbd.c to give me the pointer to showel in input from 
> /dev/tty0.
> I've been discussing this on #qemu and got directed to look at 
> ui/curses.c, which is likely closest to what I need to do, but only 
> for input and more lowlevel. They also pointed me to your work, so 
> I've asked about that, if I can use it.
> Seems I'll try to start from the curses.c then, if that's better way 
> (my knowledge of qemu codebase is zero and I'm not a good developer 
> either, but I may try in my free time since I need this and I'd like 
> to see it upstream - there are more people trying vga passthrough who 
> possibly need this :)) At least keyboard, mouse is nice to have, but 
> that can be done with the virtio-input, it's not crucial eg. during 
> installation where you may not have those drivers.
>
> > > Is there any technical reason it can't/shouldn't be done with your 
> > > devices?
> > That wouldn't be related to virtio-input at all, and also probably
> > wouldn't be able to share much code with virtio-input-host as qemu would
> > have to interpret the linux input layer events then instead of passing
> > them through to the guest without looking at them much.
> >
> > > also, do you have any public testing VMs, that are known to work with
> > > synaptics touchpad? I'm trying out the virtio devices, I've managed to
> > > get trackpoint working, but touchpad kills the guest X. I'd like to 
> > > make
> > > sure the problem is guest-side. If you don't have one, I'll try to make
> > > more experiments myself to see where the problem is.
> > I'd suspect X in the guest is surprised to find the touchpad attached
> > via virtio instead of ps/2, possibly because it tries to configure the
> > touchpad and doesn't find the knobs needed to do so ...
> I was just wondering if you don't have a bunch of testing VMs that 
> you've already used for this to quickly rule out one side (host or 
> guest). I've tested it on debian only so far (jessie-backports 
> kernel), I may install few more to see if it's not some unrelated bug 
> (it crashes on floating point exception in synaptics driver).
> > cheers,
> >    Gerd
> Thanks for the reply,
> Gh.