From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932341AbcG1Oq6 (ORCPT ); Thu, 28 Jul 2016 10:46:58 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44206 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758735AbcG1Oqu (ORCPT ); Thu, 28 Jul 2016 10:46:50 -0400 Date: Thu, 28 Jul 2016 07:47:04 -0700 From: Greg KH To: Max Staudt Cc: "Theodore Ts'o" , One Thousand Gnomes , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 8250: option 'force_polling' for buggy IRQs Message-ID: <20160728144704.GA12984@kroah.com> References: <1469468175-15704-1-git-send-email-mstaudt@suse.de> <20160725174712.GA5752@kroah.com> <20160726150856.GA15676@kroah.com> <20160727130923.4c20524b@lxorguk.ukuu.org.uk> <2b140616-c210-e754-a854-cd6a5675277d@suse.de> <20160727133348.GB20032@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 28, 2016 at 11:59:20AM +0200, Max Staudt wrote: > On 07/27/2016 03:33 PM, Theodore Ts'o wrote: > > On Wed, Jul 27, 2016 at 02:14:24PM +0200, Max Staudt wrote: > >>> If you set the IRQ to 0 it should poll anyway (0 means 'no IRQ') so I > >>> don't think the option is needed. At least it seems sufficient to get me > >>> by when I meet buggy PC BIOSes and the like > >> > >> That's exactly what the patch does - but if there is already a way to set the > >> IRQ to 0, I would of course prefer to use that. > >> > >> It seems I haven't found the trick you're using - could you please tell me how > >> you set the IRQ to 0? I can't change it in the BIOS, so I have to do it at > >> the kernel level at the latest. > > > > So the problem is that you can't use setserial because you want to use > > this port for your console? And so you don't want to set it in an initscript? > > Exactly. There is no initscript when I use rdinit=/bin/bash, so I have no choice > but to set it in the kernel. As soon as /bin/bash accesses /dev/ttyS0, the > console hangs. > > > > The one thing which is really unfortunate with this patch is that it's > > a global, so it forces polling for *all* serial ports. And it may be > > that it's only base ports on the motherboard which needs this hack. > > I agree, and I thought about it, but since this is meant for a very limited > audience, I think a catch-all is the easiest solution - both in terms of > implementation as well as ease of use. > > It's not meant for general consumption anyway. Then I really don't want to have to maintain and support such a kernel option for 20+ years, just because of one broken system out there like this. There are workarounds for this, as you have seen, including booting with a "real" userspace, so I don't want to take this patch. thanks, greg k-h