On Fri, 15 Jun 2012 09:57:49 +0200 Gerd Hoffmann <kra...@redhat.com> wrote:
> Hi, > > >> It seems we need to notice user when inputted keys are more than 16. > > > > Hi Gerd, > > > > When I use 'sendkey' command to send key-series to guest, some keyboard > > events will be send. There is a limitation (16) that was introduced by this > > old commit c8256f9d (without description). Do you know the reason? > > Probably hardware limitation, ps/2 keyboards can buffer up to 16 keys IIRC. Then the perfect thing to do would be to drop the MAX_KEYCODES check from the sendkey command and move bounds checking down to the device emulation code. However, this will require a bit of code churn if we do it for all devices, and won't buy us much, as the most likely reason for the error is a client/user trying to send too many keys in parallel to the guest, right? If this is right, then I think that the best thing to do would be to drop the MAX_KEYCODES check from the sendkey command and document that devices can drop keys if too many of them are sent in parallel or too fast (we can mention ps/2 as an example of a 16 bytes limit). > > Likewise the usb hid devices can buffer up to 16 events. In that case > it is just a qemu implementation detail and not a property of the > hardware we are emulating, so it can be changed. Not trivially though > as the buffer is part of the migration data, so it is more work that > just changing a #define.
