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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,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 B18B2C433E0 for ; Tue, 19 Jan 2021 20:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62BF42310B for ; Tue, 19 Jan 2021 20:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391931AbhASUFr (ORCPT ); Tue, 19 Jan 2021 15:05:47 -0500 Received: from m42-8.mailgun.net ([69.72.42.8]:54213 "EHLO m42-8.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728987AbhASUDv (ORCPT ); Tue, 19 Jan 2021 15:03:51 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1611086608; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=wQthR0ZyWcyEAUlTzMNFc3z3zw4jUtMWz6880r91VxQ=; b=DSPs+oT69uQhqRbBJHQQXv9aXB2MJ/qkqdTerP87Hnf0OESXj3vFkA/+4mw+YwRBGYOhsrsV 1/3h+LTe2/Wcn/g8iUeBeI5LZoGAr3mhCluAEbAs4OGiLQS7nMLB5KCNF+/RvIzoGjq7nmDf jmxpofq4wuCiNjYuBSrFOfc/nLg= X-Mailgun-Sending-Ip: 69.72.42.8 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-west-2.postgun.com with SMTP id 60073af175e5c01cbae0059b (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 19 Jan 2021 20:02:57 GMT Sender: mkalikot=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 382A4C43461; Tue, 19 Jan 2021 20:02:57 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: mkalikot) by smtp.codeaurora.org (Postfix) with ESMTPSA id 36CCDC433ED; Tue, 19 Jan 2021 20:02:56 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 19 Jan 2021 12:02:56 -0800 From: mkalikot@codeaurora.org To: Masahiro Yamada Cc: Jeff Johnson , Linux Kbuild mailing list , Prasad Sodagudi , Elliot Berman , Nick Desaulniers , Michal Marek , Linux Kernel Mailing List Subject: Re: [PATCH v2 2/2] kbuild: handle excessively long argument lists In-Reply-To: References: <1610500731-30960-2-git-send-email-jjohnson@codeaurora.org> <1610660990-18812-1-git-send-email-jjohnson@codeaurora.org> <4c02050c4e95e4cb8cc04282695f8404@codeaurora.org> Message-ID: <8ddd0f29e30684ce9fcd2dd19a104bd2@codeaurora.org> X-Sender: mkalikot@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-15 13:53, Masahiro Yamada wrote: > On Sat, Jan 16, 2021 at 5:15 AM wrote: >> >> On 2021-01-14 17:12, Masahiro Yamada wrote: >> > On Fri, Jan 15, 2021 at 6:50 AM Jeff Johnson >> > wrote: >> >> >> >> From: Mahesh Kumar Kalikot Veetil >> >> >> >> Modules with a large number of compilation units may be >> >> exceeding AR and LD command argument list. Handle this gracefully by >> >> writing the long argument list in a file. The command line options >> >> read from file are inserted in place of the original @file option. >> >> >> >> The usage is well documented at >> >> https://www.gnu.org/software/make/manual/html_node/File-Function.html >> >> >> >> Signed-off-by: Mahesh Kumar Kalikot Veetil >> >> Signed-off-by: Jeff Johnson >> >> --- >> > >> > >> > >> > >> > First, is this a real problem? >> > If so, which module is exceeding the command line limit? >> >> On 2021-01-14 17:12, Masahiro Yamada wrote: >> > First, is this a real problem? >> > If so, which module is exceeding the command line limit? >> >> Mahesh & I appreciate all of the feedback. >> >> The issue is seen in an Android environment with an out-of-tree >> driver. The combination of long path names and a large number >> of source files is leading to the issue. >> >> Since Mahesh & I are not Kbuild gurus, is there an alternative >> solution to this issue? >> >> Jeff > > > I see. > > The support for out-of-tree modules > is not nice in this regard, but fixing it > would need many changes. > Agree with that. I checked the same after your first comment on this thread. It needs changes in multiple layers of makefiles. > > The long-term solution might be to upstream your driver, > but it might not be possible. > > > > > > > One cheesy workaround might be to point the module path > via a symbolic link. > > > Let's say your module is located in a very deep > directory, > /home/foo/long/long/.../path/to/your/module > > > make M=/home/foo/long/long/.../path/to/your/module modules > > would fail due to the too long command line. > > > > > First, create a symbolic link as follows: > > ln -s /home/foo/long/long/.../path/to/your/module mod_dir > > > Then, pass the symbolic link to M= option. > > make M=mod_dir modules Thanks for the suggestion. Earlier, we have used a similar workaround of using relative path instead of absolute to reduce the command line length. What's your input on the following approach where we link object files in different stages to reduce the command line length. ./Makefile # foo.c is combined and final module. obj-m = fooa.o foob.o fooc.o # link already combined object files fooc-y := fooa.o foob.o # combine into different groups fooa-y := foo1.o foo2.o foob-y := foo3.o foo4.o .... Note: We need to add MODULE_LICENSE in every group. make -C ../linux-kbuild M=/local/mnt2/workspace/dev/foo modules CC [M] /local/mnt2/workspace/dev/foo/foo1.o CC [M] /local/mnt2/workspace/dev/foo/foo2.o LD [M] /local/mnt2/workspace/dev/foo/fooa.o CC [M] /local/mnt2/workspace/dev/foo/foo3.o CC [M] /local/mnt2/workspace/dev/foo/foo4.o LD [M] /local/mnt2/workspace/dev/foo/foob.o LD [M] /local/mnt2/workspace/dev/foo/fooc.o MODPOST /local/mnt2/workspace/dev/foo/Module.symvers CC [M] /local/mnt2/workspace/dev/foo/fooa.mod.o LD [M] /local/mnt2/workspace/dev/foo/fooa.ko CC [M] /local/mnt2/workspace/dev/foo/foob.mod.o LD [M] /local/mnt2/workspace/dev/foo/foob.ko CC [M] /local/mnt2/workspace/dev/foo/fooc.mod.o LD [M] /local/mnt2/workspace/dev/foo/fooc.ko