From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 24 Nov 2009 22:10:12 +0100 (CET) Received: from gate.crashing.org ([63.228.1.57]:48261 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S1493578AbZKXVKH (ORCPT ); Tue, 24 Nov 2009 22:10:07 +0100 Received: from [IPv6:::1] (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.13.8) with ESMTP id nAOL9Dbn023474; Tue, 24 Nov 2009 15:09:13 -0600 Subject: Re: Time to make PCI_MSI default y ? From: Benjamin Herrenschmidt To: Ralf Baechle Cc: Michael Ellerman , linux-pci , linux@arm.linux.org.uk, "tony.luck" , fenghua.yu@intel.com, "David S.Miller" , Thomas Gleixner , mingo@redhat.com, Peter Anvin , linux-mips@linux-mips.org, David Daney In-Reply-To: <20091124125309.GB5749@linux-mips.org> References: <1259030388.20596.5.camel@concordia> <20091124125309.GB5749@linux-mips.org> Content-Type: text/plain; charset="UTF-8" Date: Wed, 25 Nov 2009 08:09:12 +1100 Message-ID: <1259096952.16367.134.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 25106 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: benh@kernel.crashing.org Precedence: bulk X-list: linux-mips On Tue, 2009-11-24 at 12:53 +0000, Ralf Baechle wrote: > On Tue, Nov 24, 2009 at 01:39:48PM +1100, Michael Ellerman wrote: > > > Having just hit a build-break caused by a distro building with > > PCI_MSI=n, I set out to make it default y for powerpc. Unfortunately > > that's not possible, because it's in drivers/pci/Kconfig. > > > > So is it time to make it default y for everyone? It seems to me having > > it off is more likely to cause problems than having it on these days, > > though I'm not sure if that is true for all archs. > > > > An arch that really didn't want it default y could conditionally select > > ARCH_SUPPORTS_MSI, like x86 does already. > > On MIPS the age of MSI only recently started; once single platform (Cavium) > out of all the many uses it. Cavium does a "select ARCH_SUPPORTS_MSI" but > not "select PCI_MSI" because not all platform variants actually have PCI. > > We should not give a user a chance to select something wrong in kconfig > thus automatically as many options for a platform as possible is a good > thing - after all the kconfig dialog for any given platfrom has become > painfully long. And we really should have to avoid users having to know > that the Frobnic 2000 they're trying to upgrade the kernel for requires > MSI to work ... Still... select has nasty issues. I think default y is fine here. For platforms that don't need it, make sure their defconfigs don't have it set... Or maybe default y if (X86 || PPC) Cheers, Ben.