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=-9.1 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,USER_AGENT_GIT 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 629EDC43219 for ; Thu, 25 Apr 2019 20:31:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3772E206A3 for ; Thu, 25 Apr 2019 20:31:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=rasmusvillemoes.dk header.i=@rasmusvillemoes.dk header.b="Gv8abTzq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731094AbfDYUbH (ORCPT ); Thu, 25 Apr 2019 16:31:07 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:43947 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728011AbfDYUbH (ORCPT ); Thu, 25 Apr 2019 16:31:07 -0400 Received: by mail-ed1-f66.google.com with SMTP id j20so1107917edq.10 for ; Thu, 25 Apr 2019 13:31:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=glQPnL4sW8XWVHXeXK/MLZZpZFsTphMoxIctEosK2tc=; b=Gv8abTzqyEqzsx5HSyGWB4F138/aW4b1L5C9HK1fBVoeUE+2hffUyiyueOH3f/Ij6v oxN1Ii2Dc8jG4WHXWT7sYcWH8N+JeKoTJc9PJNrP8EdKfFZJz12ZEidUfT6IcrHxEx3a T/QLIe6oES4SyLPMhZq6bOMjaEo5kFeB4W4Aw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=glQPnL4sW8XWVHXeXK/MLZZpZFsTphMoxIctEosK2tc=; b=L/2Zd0Ol9Vm6rjQBuwjDDjWUvQKp19YoyiAvNHeyDP/t83Fp3zN5nHVsth/wih5Nd6 7GLHCM3/srwd8FYxfhYGa4jW0DbHNJn6tpWa1JqCDqIZHsXgGzn+TPKJCjLzS6vzi9rC vBgMJIOClzX7fLWgjSeRFpHbP5ALTFOugk/PNwGh3XhU5cSABkB+0gtYrwfXYMjl1nRk UgQgWEJ5iwjuiJ9uP2xo++1IOLNFPI9zGqTjDHXNYVx2LmrKlbBnXdQ43KCYdzIh2Res qM6LbJF2DCoewmzPaNcYju9EKRdLxrzcpjdXsNgPHDQKs0KBDnQe60NhsblBzuRmR2De sNIw== X-Gm-Message-State: APjAAAVkWTFSBAEhOKXZbSg1F0pVqijw7gYZeUL/Azas1TDL+Rct94CP dBS6J3g5fvxDa/LJFefm/W1dxq4FzgwXtxju X-Google-Smtp-Source: APXvYqzxc1GBAvX4pAcNSXGdonuVZmtIHGHo3vJGI2k1wymEZrttua1TgJEXUIkS+1lT2km3amZOIw== X-Received: by 2002:a17:906:11d2:: with SMTP id o18mr20208570eja.123.1556224265071; Thu, 25 Apr 2019 13:31:05 -0700 (PDT) Received: from prevas-ravi.prevas.se (ip-5-186-118-63.cgn.fibianet.dk. [5.186.118.63]) by smtp.gmail.com with ESMTPSA id 10sm4159585ejn.37.2019.04.25.13.31.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Apr 2019 13:31:04 -0700 (PDT) From: Rasmus Villemoes To: Greg Kroah-Hartman , Arnd Bergmann , "Darren Hart (VMware)" , Mattias Jacobsson <2pi@mok.nu> Cc: Jeff Mahoney , Andrew Morton , Rasmus Villemoes , linux-kernel@vger.kernel.org Subject: [PATCH] mod_devicetable.h: reduce sizeof(struct of_device_id) by 80 bytes Date: Thu, 25 Apr 2019 22:31:01 +0200 Message-Id: <20190425203101.9403-1-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. To verify, I first had the 0day bot chew on a patch adding a dummy extremely long .compatible string, and I did get an email saying that the patch resulted in lots of new "warning:initializer-string-for-array-of-chars-is-too-long" warnings. Then I had it chew on a version of this patch reducing to 46 (because gcc unfortunately does not warn when the literal sans the terminating nul just fits), and got a SUCCESS mail listing 107 config/arch combinations. For an arm imx_v6_v7_defconfig kernel, .rodata becomes 70K smaller; .init.data shrinks by another ~13K, making the whole kernel image about 83K, or 0.3%, smaller. Signed-off-by: Rasmus Villemoes --- include/linux/mod_devicetable.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h index 448621c32e4d..502629bdac2e 100644 --- a/include/linux/mod_devicetable.h +++ b/include/linux/mod_devicetable.h @@ -241,7 +241,7 @@ struct sdw_device_id { struct of_device_id { char name[32]; char type[32]; - char compatible[128]; + char compatible[48]; const void *data; }; -- 2.20.1