From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F98AC43381 for ; Tue, 5 Mar 2019 22:08:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FB50204EC for ; Tue, 5 Mar 2019 22:08:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=agner.ch header.i=@agner.ch header.b="glNf1Gom" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726877AbfCEWIu (ORCPT ); Tue, 5 Mar 2019 17:08:50 -0500 Received: from mail.kmu-office.ch ([178.209.48.109]:56876 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726052AbfCEWIt (ORCPT ); Tue, 5 Mar 2019 17:08:49 -0500 Received: from webmail.kmu-office.ch (unknown [IPv6:2a02:418:6a02::a3]) by mail.kmu-office.ch (Postfix) with ESMTPSA id EBD525C0816; Tue, 5 Mar 2019 23:08:45 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1551823726; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+QkaNjiYlpG0A1tWiuj1oUtWf14BsbsS4Ofyh8yo478=; b=glNf1GomYWS3guyqu3yCa6ljb/npcfEzzOFMQwyGZh3+XG+p0NJBhKwcDro2ah0TTIUf5G XtjfJzHT43uskrzN+su0DTjOWXxOsKxA1M7g55pkUUUnZo7lGWNHfm6k9317B5VLHKyd/8 9XnZnonLf7Kj6ya3GCnHgm6TNu7Z4Fo= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Date: Tue, 05 Mar 2019 23:08:45 +0100 From: Stefan Agner To: Michal Hocko Cc: Russell King - ARM Linux , LKML , linux-kernel-owner@vger.kernel.org Subject: Re: arch/arm/kernel/setup.c fails to compile for NOMMU In-Reply-To: <20180406095656.GJ8286@dhcp22.suse.cz> References: <20170818112402.GB18499@dhcp22.suse.cz> <20170824161741.GX20805@n2100.armlinux.org.uk> <20170825064540.GB25498@dhcp22.suse.cz> <20180406095656.GJ8286@dhcp22.suse.cz> Message-ID: X-Sender: stefan@agner.ch User-Agent: Roundcube Webmail/1.3.7 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Michal, On 06.04.2018 11:56, Michal Hocko wrote: > On Fri 25-08-17 08:45:40, Michal Hocko wrote: >> On Thu 24-08-17 17:17:41, Russell King - ARM Linux wrote: >> > On Fri, Aug 18, 2017 at 01:24:02PM +0200, Michal Hocko wrote: >> > > Hi Russel, >> > > I have a battery of configs for compile testing and for some time I've >> > > been seeing the following compilation error with nommu config (attached) >> > > >> > > arch/arm/kernel/setup.c: In function 'reserve_crashkernel': >> > > arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first >> > > use in this function) >> > > crash_size, SECTION_SIZE); >> > > >> > > I didn't get to look what is going on here, maybe my config is just too >> > > artificial but the primary reason is that SECTION_SIZE is not defined in >> > > pgtable-nommu.h. To be honest I am not familiar with nommu very much and >> > > it smells like the whole reserve_crashkernel doesn't really make any >> > > sense on those configs. Could you have a look what is the best fix >> > > please? >> > >> > Hi, >> > >> > I suspect that mach-netx has never been tested in nommu configurations >> > (ditto for many of the older platforms, which pre-date merging nommu >> > support.) >> > >> > Maybe the best solution is to make these old platforms depend on MMU. >> > >> > However, I'm wondering whether kexec makes sense for !MMU - that's >> > probably something that hasn't been tested and doesn't actually work. >> > So maybe another approach would be to make kexec depend on MMU for >> > ARM - but I'm afraid I don't really know. >> >> Yeah, I've disabled KEXEC in my testing config. All I do care about is >> to test nommu specific code paths in MM code. >> >> > I only have very limited nommu experience. >> >> me too >> >> So what would you say about the following? > > It's been some time and it seems this has fallen between cracks. Is this > worth puruing or I should just forget about it and drop it on the floor? I actually came across this issue during some randconfig testing. Your change looks good to me: Reviewed-by: Stefan Agner Fixes for the ARM core usually go through Russell's patch tracker, did you submit you patch there? See also: https://www.arm.linux.org.uk/developer/patches/info.php -- Stefan >> --- >> From 2707f3bf00181bbc9dcf6a1f287eb7369141e955 Mon Sep 17 00:00:00 2001 >> From: Michal Hocko >> Date: Fri, 25 Aug 2017 08:40:09 +0200 >> Subject: [PATCH] arm: make kexec depend on MMU >> >> arm nommu config with KEXEC enabled doesn't compile >> arch/arm/kernel/setup.c: In function 'reserve_crashkernel': >> arch/arm/kernel/setup.c:1005:25: error: 'SECTION_SIZE' undeclared (first >> use in this function) >> crash_size, SECTION_SIZE); >> >> since 61603016e212 ("ARM: kexec: fix crashkernel= handling") which is >> over one year without anybody noticing. I have only noticed beause of >> my testing nommu config which somehow gained CONFIG_KEXEC without >> an intention. This suggests that nobody is actually using KEXEC >> on nommu ARM configs. It is even a question whether kexec works with >> nommu. >> >> Make KEXEC depend on MMU to make this clear. If somebody wants to enable >> there will be probably more things to take care. >> >> Signed-off-by: Michal Hocko >> --- >> arch/arm/Kconfig | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> index 3f4aa9179337..c8603195d7fc 100644 >> --- a/arch/arm/Kconfig >> +++ b/arch/arm/Kconfig >> @@ -2003,6 +2003,7 @@ config KEXEC >> bool "Kexec system call (EXPERIMENTAL)" >> depends on (!SMP || PM_SLEEP_SMP) >> depends on !CPU_V7M >> + depends on MMU >> select KEXEC_CORE >> help >> kexec is a system call that implements the ability to shutdown your >> -- >> 2.13.2 >> >> -- >> Michal Hocko >> SUSE Labs