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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4436C433EF for ; Fri, 4 Mar 2022 15:35:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240377AbiCDPgT (ORCPT ); Fri, 4 Mar 2022 10:36:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233371AbiCDPgQ (ORCPT ); Fri, 4 Mar 2022 10:36:16 -0500 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8F1391C57FE; Fri, 4 Mar 2022 07:35:28 -0800 (PST) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1nQ9xm-0008Sv-00; Fri, 04 Mar 2022 16:35:26 +0100 Received: by alpha.franken.de (Postfix, from userid 1000) id 3620EC0F8D; Fri, 4 Mar 2022 16:35:17 +0100 (CET) Date: Fri, 4 Mar 2022 16:35:17 +0100 From: Thomas Bogendoerfer To: Tiezhu Yang Cc: Mike Rapoport , Andrew Morton , Xuefeng Li , linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/4] MIPS: Refactor early_parse_mem() to fix mem= parameter Message-ID: <20220304153517.GA28487@alpha.franken.de> References: <1646108941-27919-1-git-send-email-yangtiezhu@loongson.cn> <1646108941-27919-2-git-send-email-yangtiezhu@loongson.cn> <20220304151052.GA27642@alpha.franken.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220304151052.GA27642@alpha.franken.de> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 04, 2022 at 04:10:52PM +0100, Thomas Bogendoerfer wrote: > On Tue, Mar 01, 2022 at 12:28:58PM +0800, Tiezhu Yang wrote: > > According to Documentation/admin-guide/kernel-parameters.txt, > > the kernel command-line parameter mem= means "Force usage of > > a specific amount of memory", but when add "mem=3G" to the > > command-line, kernel boot hangs in sparse_init(). > > > > This commit is similar with the implementation of the other > > archs such as arm64, powerpc and riscv, refactor the function > > early_parse_mem() and then use memblock_enforce_memory_limit() > > to limit the memory size. > > > > With this patch, when add "mem=3G" to the command-line, the > > kernel boots successfully, we can see the following messages: > > unfortunately this patch would break platforms without memory detection, > which simply use mem=32M for memory configuration. Not sure how many > rely on this mechanism. If we can make sure nobody uses it, I'm fine > with your patch. maybe we could add a CONFIG option, which will be selected by platforms, which don't need/want this usermem thing. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]