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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 34F08C43219 for ; Fri, 26 Apr 2019 11:06:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E763A206E0 for ; Fri, 26 Apr 2019 11:06:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726152AbfDZLGN (ORCPT ); Fri, 26 Apr 2019 07:06:13 -0400 Received: from mout.kundenserver.de ([212.227.126.135]:49407 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726026AbfDZLGN (ORCPT ); Fri, 26 Apr 2019 07:06:13 -0400 Received: from [192.168.1.110] ([95.117.100.117]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.167]) with ESMTPSA (Nemesis) id 1MFbFW-1hZuaM0ohC-00H6I9; Fri, 26 Apr 2019 13:06:00 +0200 Subject: Re: [PATCH] mod_devicetable.h: reduce sizeof(struct of_device_id) by 80 bytes To: Rasmus Villemoes , Greg Kroah-Hartman , Arnd Bergmann , "Darren Hart (VMware)" , Mattias Jacobsson <2pi@mok.nu> Cc: Jeff Mahoney , Andrew Morton , linux-kernel@vger.kernel.org References: <20190425203101.9403-1-linux@rasmusvillemoes.dk> From: "Enrico Weigelt, metux IT consult" Organization: metux IT consult Message-ID: <62959593-6029-e66e-ebee-314db7aa6f10@metux.net> Date: Fri, 26 Apr 2019 13:05:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190425203101.9403-1-linux@rasmusvillemoes.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:xAHKBzNkH5dQRMa5vm6XP6kXAmIjZcyXPv07AcL8d1eJs8+bcCw Yi4iT6pRljUyZ7eSvUVoqaezREp58q+riYBqOosxo5qAGQrx4IviHOvVSB5uBHm1X9635xn 0KupHe2UpAgnQYbl/fUnacfTIRCpAMxYo4F5sjbz30060omP8bCIKiAKi/xZBSBPzujOFNN 5/cA2vbqT3VOb5zBQjTlQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:GS6iPp9pRi4=:xxoBiSkHGi5cmhxL7nzIGt 1KLVisa+pqTl2oSJBJqwLnz+t6F8Ft5yiVL4HGTowbrY07/TT9sMxZLzSEo4SqS7QMmu6CCB4 Ww2aNi+GjJWO30xcjmOX5Hq3wAVH+7SaV7RerUFkZsDBXCgpmzfHSM9aHSqsFQz5V2t6kPlIO 8IiK7qkhGjBB3ex8KXj6He8zau/pvR8fG6QE5PabZ3aj6l+FMrrQy94qUtnVl133U0LYyU3B3 blw6qByAK8QlUV6ZEAZgq0FgCoo9dsRNDrPuc+X8dJyMNCgtpZnvTSobn2d9O/3YE+aLMIFHn +tne7c4BQpPCvSZAwnJbalWen9egUqV4J+WeXKMzBY9rkMjbssifzr7vVzqRfA1BVPtzjro4E wcenAL+w+0Vf3DJVSjNXyoW0KSZEF6g6YT56j7AOgJL1X0SCpeFcNsfJ6FpizV2sw3E38B2nM jNb82aC4NlkCtpwT4SanPF4QIyzAe/AEkSbvnSgGv7F0m8uQ3CXnpUFLEFgzQcj7Nlf9sc6Gx TaayJ3S5OjRqa6SFS1+7D54P+JLtQBUbDarO7PVGihyUXC6hzRR7eVPKw6MYO6VZValarzEzM BmFd7tm8tmKQu2vXxevLXi+3JtaYVSGq0ijzXdBxmii7Fx9TZazrgjSFYiKT67k0j3MG/MgcF EsXSwWxe/vb3RL4/Lg80A2fUGspaV0sN+W83enwcJ1QGJVn9bk1Wel5FaCPGEJ0Y70GO8RSoY UVCfhlrAIgvwOf/ucYpEkRmh+G5EbekofoWsufgiRUL+TJXJE6XaNhsjxbc= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25.04.19 22:31, Rasmus Villemoes wrote: Hi, > A typical kernel image has hundreds of static struct of_device_id > instances (a lot of which are sentinel all-zeroes), each occupying > ~200 bytes. Nobody initializes the .compatible member with strings > anywhere near 128 bytes, so a lot of that memory is simply wasted. I just wonder whether it has to be a fixed size array at all, instead of an const char* pointer. Using a pointer should, IMHO, offer even more savings while not having the size limit at all. Is that struct copied as-is somewhere ? --mtx -- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287