From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35695) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ecCCd-0001m3-TZ for qemu-devel@nongnu.org; Thu, 18 Jan 2018 10:34:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ecCCb-0005sg-2y for qemu-devel@nongnu.org; Thu, 18 Jan 2018 10:34:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:8833) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ecCCa-0005sF-Sy for qemu-devel@nongnu.org; Thu, 18 Jan 2018 10:34:05 -0500 References: <20180112125854.18261-1-kraxel@redhat.com> <20180112125854.18261-11-kraxel@redhat.com> <20180118133643.GP19695@redhat.com> <20180118141256.GS19695@redhat.com> <85686228-03dd-a7fc-1477-f27d09de5007@redhat.com> From: Paolo Bonzini Message-ID: <5eb947cb-6481-9081-0574-306858f985e0@redhat.com> Date: Thu, 18 Jan 2018 16:33:49 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PULL 10/14] ui: fix VNC client throttling when audio capture is active List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: "Daniel P. Berrange" , Gerd Hoffmann , QEMU Developers On 18/01/2018 15:50, Peter Maydell wrote: > On 18 January 2018 at 14:46, Paolo Bonzini wrote: >> On 18/01/2018 15:12, Daniel P. Berrange wrote: >>>> In addition to that, do we support a >= 2 GiB framebuffer at all? (Even >>>> with unsigned ints, Coverity would rightly complain about a truncated >>>> 32-bit multiplication being assigned to a 64-bit value). >>> client_width/client_height are values that are initialized from the >>> graphics card frontend config, and thus limited by amount of video >>> RAM QEMU allows. bytes_per_pixel is limited to 8/16/32. >>> >>> So I think we're safe from 2GB overflow in any normal case. >>> >>> That said, VGA RAM size is configurable, so I'm curious what would happen >>> if someone configured an insanely large VGA RAM and asked for a big frame >>> buffer in guest. >>> >>> VNC is protocol limited to uint16 for width/height size, and so is X11 >>> so I imagine some exploding behavour would follow :-) >> >> Indeed, and even 2^16 x 2^16 * 32bpp is already 34 bits. So perhaps we >> should limit VNC to 16384 pixels on each axis (maximum frame buffer size >> 1 GiB). > > Google says you can already get graphics cards that can do 15360x8640, > which is really quite close to that 16384 limit... Then we can do 32767 * 16384 * 4, but I'm a bit afraid of off-by-ones. Paolo