From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261522AbVGaCTO (ORCPT ); Sat, 30 Jul 2005 22:19:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261538AbVGaCTO (ORCPT ); Sat, 30 Jul 2005 22:19:14 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:8348 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S261522AbVGaCTM (ORCPT ); Sat, 30 Jul 2005 22:19:12 -0400 To: Lee Revell Cc: Ralf Hildebrandt , linux-kernel@vger.kernel.org Subject: Re: ALSA, snd_intel8x0m and kexec() don't work together (2.6.13-rc3-git4 and 2.6.13-rc3-git3) References: <20050721180621.GA25829@charite.de> <20050722062548.GJ25829@charite.de> <200507221614.28096.vda@ilport.com.ua> <20050722131825.GR8528@charite.de> <1122054941.877.6.camel@mindpipe> From: ebiederm@xmission.com (Eric W. Biederman) Date: Sat, 30 Jul 2005 20:19:00 -0600 In-Reply-To: <1122054941.877.6.camel@mindpipe> (Lee Revell's message of "Fri, 22 Jul 2005 13:55:41 -0400") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Lee Revell writes: > On Fri, 2005-07-22 at 15:18 +0200, Ralf Hildebrandt wrote: >> * Denis Vlasenko : >> >> > Not happening here on 2.6.12: >> >> 2.6.12 didn't have kexec (unless it's a -mm kernel) >> So how could you boot using kexec then? >> > > Is kexec supposed to be transparent to all the subsystems, or does ALSA > have to know how to stop all DMA in order for kexec to work? It is fairly transparent. device_shutdown on reboot should stop DMA but that is not kexec specific. kexec may be the only way the code path is easily tested. The basic requirement from the kexec side is that the drivers be able to bring back the device from the state they left it on reboot. So in essence it is transparent. But if your driver is not robust you can have problems. The fact the new kernel was coming up indicates that kexec worked but the driver did not successfully initialize, the hardware from the state it placed it in during shutdown. Eric