From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261408AbVFDSXU (ORCPT ); Sat, 4 Jun 2005 14:23:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261412AbVFDSXU (ORCPT ); Sat, 4 Jun 2005 14:23:20 -0400 Received: from colo.lackof.org ([198.49.126.79]:7145 "EHLO colo.lackof.org") by vger.kernel.org with ESMTP id S261408AbVFDSXO (ORCPT ); Sat, 4 Jun 2005 14:23:14 -0400 Date: Sat, 4 Jun 2005 12:26:45 -0600 From: Grant Grundler To: Alan Stern Cc: Vivek Goyal , linux kernel mailing list , Greg KH , Fastboot mailing list , Morton Andrew Morton , "Eric W. Biederman" , Bodo Eggert <7eggert@gmx.de>, Dipankar Sarma , Grant Grundler , awilliam@fc.hp.com, bjorn.helgaas@hp.com Subject: Re: [RFC/PATCH] Kdump: Disabling PCI interrupts in capture kernel Message-ID: <20050604182645.GD19823@colo.lackof.org> References: <1117882628.42a1890479c23@imap.linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Home-Page: http://www.parisc-linux.org/ User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 04, 2005 at 11:35:59AM -0400, Alan Stern wrote: > On Sat, 4 Jun 2005, Vivek Goyal wrote: > > > Hi Alan, I know very little about consoles and their working. > > I had a question. Even if console is being managed by platform firmware, in > > initial states of booting, does it require interrupts to be enabled at > > VGA contorller (at least for the simple text mode). I was quickly browsing > > through drivers/video/console/vgacon.c and did not look like that this > > console driver needed interrupts to be enabled at the controller. > > This isn't an issue for VGA, as far as I know. It applies to > architectures like PPC-64 and perhaps Alpha or PA-Risc. And I don't know > the details; ask Grant Grundler. I'm more familiar with the serial consoles and how PDC interacts with them. >>From HP, both Alex Williamson and Bjorn Helgaas know more about VGA support. I've cc'd both. > > Anyway, looks like serial consoles will always work. So at least this can be > > done for kdump case (CONFIG_CRASH_DUMP) and not generic kernel. Or, as I > > mentioned in previous mail, while pre-loading capture kernel, pass a command > > line parameter containing pci dev id of console and capture kernel does not > > disable interrupts on this console. parisc serial consoles don't need interrupts enabled. The serial device does need it's MMIO and/or IO Port range enabled (I forgot which). ISTR most serial consoles don't do DMA and thus don't need BusMaster enabled in the PCI command register either. > I suspect you're right that implementing this only in kdump kernels will > work okay. > > For people interesting in reading some old threads on the subject, here > are some pointers: > > http://marc.theaimsgroup.com/?l=linux-usb-devel&m=111055702309788&w=2 > > http://marc.theaimsgroup.com/?l=linux-kernel&m=98383052711171&w=2 wow...from 2001. That's when we first release a500 support with Debian 3.0. thanks, grant