Re: [Qemu-devel] qemu: hardware error: Failed to create USB device 'usb-tablet'

[Alexander Graf]

On 30.06.2011, at 09:20, address@hidden wrote:

> On Wed, Jun 29, 2011 at 7:25 PM, Peter Maydell <address@hidden> wrote:
>> Unfortunately there isn't a QEMU model of the ISP1761 USB controller
>> which the Versatile Express uses, so that machine model doesn't have
>> USB support. (versatilepb gets USB support via its PCI bus, but
>> there is no PCI for vexpress.)
>> 
> 
> Are you aware when can this be supported? I'm aware that Linaro's Qemu
> had something about it in TODO for their next release.
> 
> Also,
> 
> Are you aware what is the root of the problem of Qemu not being able
> to emulated correct pointer position with mouse device in VNC mode and
> requiring tablet? I'm aware of tablet vs mouse difference in specifing
> the coordinates (absolute vs relative). I'm just not aware why Qemu
> can't translate one into other correctly? I guess I must be missing
> something if this haven't been yet fixed.

For relative pointing devices, the guest does something called "mouse 
acceleration" where it tries to find out how quickly you're moving the mouse 
and set the pointer accordingly. Hence the coordinates the guest window 
management system thinks your mouse is on and the coordinates qemu would think 
they should be differ.

You can set acceleration to 1 with xset, giving you 1:1 translation of relative 
movement to absolute movement inside the guest.


Alex