From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Gortmaker Subject: Re: nommu build failures on ARM in linux-next Date: Thu, 29 May 2014 20:05:42 -0400 Message-ID: <20140530000542.GB2999@windriver.com> References: <5387661F.1050000@windriver.com> <20140529185534.GK3693@n2100.arm.linux.org.uk> <20140529234012.GL3693@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Received: from mail1.windriver.com ([147.11.146.13]:47822 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752976AbaE3AGH (ORCPT ); Thu, 29 May 2014 20:06:07 -0400 Content-Disposition: inline In-Reply-To: <20140529234012.GL3693@n2100.arm.linux.org.uk> Sender: linux-next-owner@vger.kernel.org List-ID: To: Russell King - ARM Linux Cc: "linux-next@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" [Re: nommu build failures on ARM in linux-next] On 30/05/2014 (Fri 00:40) Russell King - ARM Linux wrote: > On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote: > > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote: > > > Hi Russell, > > > > > > The allnoconfig builds in linux-next fail because __clear_cr > > > lives in mmu.c without any stub or similar in nommu.c > > > > > > Introduced by: > > > > > > commit 247e4fff3aa927ad069447e6da05bb966b70dece > > > Author: Russell King > > > Date: Sun Apr 13 18:57:29 2014 +0100 > > > > > > ARM: provide common method to clear bits in CPU control register > > > > > > Sample failure: > > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/ > > > > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that > > __clear_cr should exist in this case - but it doesn't because it's in > > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c. > > I've been looking at doing this, and while it can be done by applying > a patch on top, that's not my preferred solution. > > However, my preferred solution (which is to fix the commit) needs a bit > of rework of the patch series, and given the number of patches I'm > carrying right now, I'm just going to drop the branch out of linux-next > and hold it off until the following merge window instead. > > Even so, I suspect even with this build problem solved, that's not going > to be the end of the story for noMMU breakage... it's certainly something > that gets very little testing by anyone. I suspect it should be removed > from the mainline kernel tree rather than being a constant source of these > kinds of problems. One doesn't have to look very far to see that I'm in favour of pushing obsolete options/drivers/subsystems off a cliff if I can get away with it, so that we don't get crushed under our own weight/complexity. So if you really think it is time for ARM noMMU to go, I'll volunteer to craft up a removal series for you for 3.17 -- just say the word. Paul. -- > > -- > FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly > improving, and getting towards what was expected from it. From mboxrd@z Thu Jan 1 00:00:00 1970 From: paul.gortmaker@windriver.com (Paul Gortmaker) Date: Thu, 29 May 2014 20:05:42 -0400 Subject: nommu build failures on ARM in linux-next In-Reply-To: <20140529234012.GL3693@n2100.arm.linux.org.uk> References: <5387661F.1050000@windriver.com> <20140529185534.GK3693@n2100.arm.linux.org.uk> <20140529234012.GL3693@n2100.arm.linux.org.uk> Message-ID: <20140530000542.GB2999@windriver.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org [Re: nommu build failures on ARM in linux-next] On 30/05/2014 (Fri 00:40) Russell King - ARM Linux wrote: > On Thu, May 29, 2014 at 07:55:34PM +0100, Russell King - ARM Linux wrote: > > On Thu, May 29, 2014 at 12:53:51PM -0400, Paul Gortmaker wrote: > > > Hi Russell, > > > > > > The allnoconfig builds in linux-next fail because __clear_cr > > > lives in mmu.c without any stub or similar in nommu.c > > > > > > Introduced by: > > > > > > commit 247e4fff3aa927ad069447e6da05bb966b70dece > > > Author: Russell King > > > Date: Sun Apr 13 18:57:29 2014 +0100 > > > > > > ARM: provide common method to clear bits in CPU control register > > > > > > Sample failure: > > > http://kisskb.ellerman.id.au/kisskb/buildresult/11264405/ > > > > ALIGNMENT_TRAP depends on CPU_CP15_MMU, so it's quite reasonable that > > __clear_cr should exist in this case - but it doesn't because it's in > > mmu.c. I guess we need __clear_cr moved to arch/arm/kernel/setup.c. > > I've been looking at doing this, and while it can be done by applying > a patch on top, that's not my preferred solution. > > However, my preferred solution (which is to fix the commit) needs a bit > of rework of the patch series, and given the number of patches I'm > carrying right now, I'm just going to drop the branch out of linux-next > and hold it off until the following merge window instead. > > Even so, I suspect even with this build problem solved, that's not going > to be the end of the story for noMMU breakage... it's certainly something > that gets very little testing by anyone. I suspect it should be removed > from the mainline kernel tree rather than being a constant source of these > kinds of problems. One doesn't have to look very far to see that I'm in favour of pushing obsolete options/drivers/subsystems off a cliff if I can get away with it, so that we don't get crushed under our own weight/complexity. So if you really think it is time for ARM noMMU to go, I'll volunteer to craft up a removal series for you for 3.17 -- just say the word. Paul. -- > > -- > FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly > improving, and getting towards what was expected from it.