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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 C6E39C3279B for ; Tue, 10 Jul 2018 14:16:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89070208E5 for ; Tue, 10 Jul 2018 14:16:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89070208E5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933558AbeGJOP5 (ORCPT ); Tue, 10 Jul 2018 10:15:57 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47510 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754265AbeGJOP4 (ORCPT ); Tue, 10 Jul 2018 10:15:56 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 63D4880D; Tue, 10 Jul 2018 07:15:56 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 316CD3F589; Tue, 10 Jul 2018 07:15:56 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id E8E921AE53F3; Tue, 10 Jul 2018 15:16:37 +0100 (BST) Date: Tue, 10 Jul 2018 15:16:37 +0100 From: Will Deacon To: Arnd Bergmann Cc: Nikunj Kela , Catalin Marinas , xe-kernel@external.cisco.com, Linux Kernel Mailing List , Linux ARM Subject: Re: [PATCH v3] arm64: add ARM64-specific support for flatmem Message-ID: <20180710141637.GB9022@arm.com> References: <20180706174724.44594-1-nkela@cisco.com> <20180710130650.GD31318@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 10, 2018 at 03:25:14PM +0200, Arnd Bergmann wrote: > On Tue, Jul 10, 2018 at 3:06 PM, Will Deacon wrote: > > On Tue, Jul 10, 2018 at 02:55:41PM +0200, Arnd Bergmann wrote: > >> On Fri, Jul 6, 2018 at 7:47 PM, Nikunj Kela wrote: > >> > Flatmem is useful in reducing kernel memory usage. > >> > One usecase is in kdump kernel. We are able to save > >> > ~14M by moving to flatmem scheme. > >> > > >> > Cc: xe-kernel@external.cisco.com > >> > Cc: Nikunj Kela > >> > Signed-off-by: Nikunj Kela > >> > --- > >> > arch/arm64/Kconfig | 3 +++ > >> > 1 file changed, 3 insertions(+) > >> > > >> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > >> > index 42c090c..f5b4c49 100644 > >> > --- a/arch/arm64/Kconfig > >> > +++ b/arch/arm64/Kconfig > >> > @@ -775,6 +775,9 @@ config ARCH_SPARSEMEM_DEFAULT > >> > config ARCH_SELECT_MEMORY_MODEL > >> > def_bool ARCH_SPARSEMEM_ENABLE > >> > > >> > +config ARCH_FLATMEM_ENABLE > >> > + def_bool y > >> > + > >> > config HAVE_ARCH_PFN_VALID > >> > def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM > >> > > >> > >> I'm getting hundreds of errors in randconfig builds with this: > > > > Damn, I was worried something like this might happen. Sorry! > > > > Does randconfig also fuzz CONFIG_EXPERT? We only added ARCH_FLATMEM_ENABLE > > so that people can hand-configure crashkernels to make them small; there will > > be plenty of situations where it's just going to cause more problems than it > > solves, so I'd be happy hiding it behind EXPERT if it helps. > > Yes, randconfig also tests EXPERT and COMPILE_TEST configurations, though I > don't test the !COMPILE_TEST ones myself, so you can also hide options from > me by making them 'depends on !COMPILE_TEST'. > > > Otherwise we can probably through a 'def_bool !NUMA' at it. > > Yes, I was going to send a patch with that next after testing it some more. > So far it's holding up. This is also what some other architectures have, so > it's probably safe. Ok, let's go with that then. If I don't see a patch from you in a day or two, I'll write one myself :) Will