From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 16 Sep 2001 09:13:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 16 Sep 2001 09:13:22 -0400 Received: from mailout03.sul.t-online.com ([194.25.134.81]:55820 "EHLO mailout03.sul.t-online.de") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Sun, 16 Sep 2001 09:13:02 -0400 From: Michael Schroeder Date: Sun, 16 Sep 2001 13:32:06 GMT Message-ID: <20010916.13320600@sirius.imsch.de> Subject: Bug in console driver? To: linux-kernel@vger.kernel.org X-Mailer: Mozilla/3.0 (compatible; StarOffice/5.2; Linux) X-Priority: 3 (Normal) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO_8859-15 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! I suppose there is a bug in the 2.4-kernel console driver (../drivers/char/console.c). It seems that (if there is a slow video device) this driver disables the handling of interrupts while writing or switching the consoles. Symptoms: If you use the VESA framebuffer, switching to another console prevents updating the internal kernel clock (jiffies, xtime) for a short time. This effect can grow up to some seconds: Load the GNU Midnight Commander (mc) and synchronize kernel clock and hardware clock with the command 'hwclock --hctosys'. Then you can see the the difference with 'hwclock && date'. # hwclock && date Sun Sep 16 10:31:33 2001 -0,154753 ... Sun Sep 10 10:31:32 CEST 2001 Now hold down the keys for a some seconds. (This switches the window of the Midnight Commander on/off many times) If you now compare the clocks you yield a difference of some seconds: # hwclock && date Sun Sep 16 10:33:17 2001 -0,456384 ... Sun Sep 16 10:33:12 CEST 2001 5 seconds - I think this is a bug. My system: Intel Pentium II, 512 MB RAM NVIdia Riva TNT2 M64 with 32 MB Kernel 2.4.4 and 2.4.7 SuSE Linux 7.2 VESA Framebuffer Greetings Michael