From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JMYyl-00064U-8n for qemu-devel@nongnu.org; Tue, 05 Feb 2008 20:21:35 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JMYyj-00063l-F4 for qemu-devel@nongnu.org; Tue, 05 Feb 2008 20:21:34 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JMYyj-00063g-9E for qemu-devel@nongnu.org; Tue, 05 Feb 2008 20:21:33 -0500 Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5] helo=grelber.thyrsus.com) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1JMYyj-00056e-0e for qemu-devel@nongnu.org; Tue, 05 Feb 2008 20:21:33 -0500 From: Rob Landley Date: Tue, 5 Feb 2008 18:43:14 -0600 References: <200802051455.10831.rob@landley.net> <47A8D00F.9040803@zytor.com> In-Reply-To: <47A8D00F.9040803@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200802051843.15163.rob@landley.net> Subject: [Qemu-devel] Re: 2.6.24 says "serial8250: too much work for irq4" a lot. Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "H. Peter Anvin" Cc: qemu-devel@nongnu.org On Tuesday 05 February 2008 15:07:27 H. Peter Anvin wrote: > Rob Landley wrote: > > When running a 2.6.24 kernel built for x86-64 under qemu via serial > > console, doing CPU-intensive things that also produce a lot of output > > (such as compiling software) tends to produce the error message in the > > title. > > > > Anybody have a clue why? It doesn't seem to cause an actual problem, but > > it's kind of annoying. > > > > (If it's a qemu issue, I can go bother them. It's possible that qemu > > isn't delivering interrupts as often as it expects, since that's limited > > by the granularity of the host timer; I know the clock in qemu can run a > > bit slow because it only gets clock interrupts when the host system isn't > > too busy to schedule the emulator. But this doesn't usually cause a > > problem. I _think_ the message is just a "this should never happen" type > > warning, which is happening to me. But I break stuff. :) > > This is because Qemu spews data to the serial port without any rate > limiting; this causes the in-kernel serial port driver to think the port > is stuck. The serial port emulation needs to make it possible to drain > the virtual FIFO every now and then, as opposed to filling it again > immediately. > > -hpa Thanks. cc'd the right list on this one. :) Rob -- "One of my most productive days was throwing away 1000 lines of code." - Ken Thompson.