From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763227AbYBGVMp (ORCPT ); Thu, 7 Feb 2008 16:12:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762785AbYBGUyM (ORCPT ); Thu, 7 Feb 2008 15:54:12 -0500 Received: from terminus.zytor.com ([198.137.202.10]:39185 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933252AbYBGUyI (ORCPT ); Thu, 7 Feb 2008 15:54:08 -0500 Message-ID: <47AB6FD7.1030502@zytor.com> Date: Thu, 07 Feb 2008 12:53:43 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Rob Landley CC: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: 2.6.24 says "serial8250: too much work for irq4" a lot. References: <200802051455.10831.rob@landley.net> <20080207123937.GC15647@elte.hu> <47AB41C8.3010001@zytor.com> <200802071413.45085.rob@landley.net> In-Reply-To: <200802071413.45085.rob@landley.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rob Landley wrote: > > Specifically, qemu isn't paravirtualized, it's fully virtualized. The same > kernel can run on real hardware just fine. (Sort of the point of the > project...) > > I can yank the warning for the kernels I build (or set PASS_LIMIT to 9999999), > but I'd rather not carry any more patches than I can avoid... > The right thing to do is to add virtual FIFO exhaustion into the Qemu device model. It really isn't a valid emulation of a UART that it has an infinite FIFO behind it that can flood the interrupt handler for an arbitrary number of fetches. I was going to give a technical description of how to do it here, but then I realized I might as well just write it up as a patch. Stay tuned. -hpa