From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53695) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfWgL-0002wl-Co for qemu-devel@nongnu.org; Fri, 15 Jun 2012 09:35:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfWgE-0005Ex-U8 for qemu-devel@nongnu.org; Fri, 15 Jun 2012 09:35:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:28289) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfWgE-0005EH-N1 for qemu-devel@nongnu.org; Fri, 15 Jun 2012 09:35:14 -0400 Date: Fri, 15 Jun 2012 10:35:31 -0300 From: Luiz Capitulino Message-ID: <20120615103531.614ed1c7@doriath.home> In-Reply-To: <4FDAEAFD.9090406@redhat.com> References: <433764b9-c58b-4b4e-8a4d-0f6cd84a25e7@zmail13.collab.prod.int.phx2.redhat.com> <4FD0326F.3010806@redhat.com> <20120611140642.06be2ee8@doriath.home> <4FD62827.4060900@us.ibm.com> <20120611142546.66871522@doriath.home> <4FD9BB06.3000509@redhat.com> <4FDAE857.6050106@redhat.com> <4FDAEAFD.9090406@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 1/6] qerror: add MAX_KEYCODES 16 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Anthony Liguori , Amos Kong , qemu-devel@nongnu.org On Fri, 15 Jun 2012 09:57:49 +0200 Gerd Hoffmann 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.