From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760511AbXGXTHZ (ORCPT ); Tue, 24 Jul 2007 15:07:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751994AbXGXTHN (ORCPT ); Tue, 24 Jul 2007 15:07:13 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:58068 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752994AbXGXTHM (ORCPT ); Tue, 24 Jul 2007 15:07:12 -0400 Message-ID: <46A64DD8.6000607@garzik.org> Date: Tue, 24 Jul 2007 15:07:04 -0400 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.12 (X11/20070719) MIME-Version: 1.0 To: Andrew Morton CC: Bjorn Helgaas , =?ISO-8859-1?Q?S=E9bastien_Du?= =?ISO-8859-1?Q?gu=E9?= , linux-kernel , Linus Torvalds Subject: Re: commit 7e92b4fc34 - x86, serial: convert legacy COM ports to platform devices - broke my serial console References: <20070724162805.76ea8328@frecb000686.frec.bull.fr> <200707240948.45916.bjorn.helgaas@hp.com> <46A63BC3.3050208@garzik.org> <20070724110946.8678d202.akpm@linux-foundation.org> In-Reply-To: <20070724110946.8678d202.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.9 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > Well I queued up a tentative revert patch but then I re-read the changlog: > > x86, serial: convert legacy COM ports to platform devices > > Make x86 COM ports into platform devices and don't probe for them > if we have PNP. > > This prevents double discovery, where a device was found both by > the legacy probe and by 8250_pnp, e.g., > > serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A > 00:02: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A If this actually causes a problem, then the drivers are buggy. We have standard APIs for checking this stuff... Turning off legacy serial probing is just a bandaid, the resource bug is still there [by definition, if double-probing problems exist]. > This also means IRDA devices without a UART PNP ID will no longer be > claimed by the serial driver, which might require changes in IRDA > drivers and administration. This was completely unaddressed, I presume? > In addition to this patch, you may need to configure a setserial init > script, e.g., /etc/init.d/setserial, so it doesn't poke legacy UART > stuff back in. On Debian, "dpkg-reconfigure setserial" with the "kernel" > option does this. So this patch breaks some userspace too? > To force the old legacy probe behavior even when we have PNPBIOS or > ACPI, load the new legacy_serial module (or build 8250 static) with > the "legacy_serial.force" option. > > So 7e92b4fc345f5b6f57585fbe5ffdb0f24d7c9b26 fixed a bunch of longstanding > nasties while breaking Sebastien's machine (at least). > > We of course want the best of both worlds here, so I'll keep the revert > patch in -mm for a while, see what happens. Although I can't immediately > see any way in which this can be fixed... I see VERY few positives, a whole lot of trouble, and a couple band-aids. Jeff