Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754699AbYAMWDl (ORCPT ); Sun, 13 Jan 2008 17:03:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754007AbYAMWDc (ORCPT ); Sun, 13 Jan 2008 17:03:32 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:33110 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753885AbYAMWDb (ORCPT ); Sun, 13 Jan 2008 17:03:31 -0500 Date: Sun, 13 Jan 2008 23:03:27 +0100 From: Pavel Machek To: Alan Cox Cc: Benjamin LaHaise , akpm@osdl.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: remove "too much work for irq" printk Message-ID: <20080113220327.GB5128@elf.ucw.cz> References: <20080112201543.GB12775@kvack.org> <20080112212457.3bf534af@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080112212457.3bf534af@lxorguk.ukuu.org.uk> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1392 Lines: 31 On Sat 2008-01-12 21:24:57, Alan Cox wrote: > On Sat, 12 Jan 2008 15:15:43 -0500 > Benjamin LaHaise wrote: > > > When using kvm with a serial console, the serial driver will print out > > "too much work for irq4" on any heavy activity (ie vi on a file repainting > > the terminal). This message is entirely spurious, as output continues to > > work fine. Remove the message as it corrupts screen output and is far too > > easy to trigger. > > NAK. This is a qemu/kvm emulation bug. The real check is there to catched > jammed IRQs and combined with the IRQ bug handling nowdays does actually > do the intended job. > > Our serial port code (correctly) interprets a continuous stream of bytes > at an impossible bit rate as an error. KVM should be emulating to some > extent at least the timing on serial interfaces or using a virtualised > interface. How can you tell apart impossible bit rate from really slow CPU, or maybe just an SMI storm, or heavy busmaster DMA? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/