From patchwork Tue Nov 15 20:29:12 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 695250 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3tJJsh2Ddnz9syB for ; Wed, 16 Nov 2016 07:30:00 +1100 (AEDT) Received: from localhost ([::1]:48658 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6kMf-0006fP-Lq for incoming@patchwork.ozlabs.org; Tue, 15 Nov 2016 15:29:57 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42000) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6kM3-0006Nb-JG for qemu-devel@nongnu.org; Tue, 15 Nov 2016 15:29:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c6kLz-0002Rn-Iu for qemu-devel@nongnu.org; Tue, 15 Nov 2016 15:29:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47664) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c6kLz-0002RR-Df for qemu-devel@nongnu.org; Tue, 15 Nov 2016 15:29:15 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8C742804FE for ; Tue, 15 Nov 2016 20:29:14 +0000 (UTC) Received: from localhost (ovpn-112-39.ams2.redhat.com [10.36.112.39]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uAFKTC8g003621; Tue, 15 Nov 2016 15:29:13 -0500 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Tue, 15 Nov 2016 20:29:12 +0000 Message-Id: <1479241752-29927-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 15 Nov 2016 20:29:14 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH] HACKING: document #include order X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Markus Armbruster , Stefan Hajnoczi Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" It was not obvious to me why "qemu/osdep.h" must be the first #include. This documents the rationale and the overall #include order. Cc: Fam Zheng Cc: Markus Armbruster Cc: Eric Blake Signed-off-by: Stefan Hajnoczi --- HACKING | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/HACKING b/HACKING index 20a9101..ced1236 100644 --- a/HACKING +++ b/HACKING @@ -1,10 +1,25 @@ 1. Preprocessor +1.1. Variadic macros + For variadic macros, stick with this C99-like syntax: #define DPRINTF(fmt, ...) \ do { printf("IRQ: " fmt, ## __VA_ARGS__); } while (0) +1.2. Include directives + +Order include directives as follows: + +#include "qemu/osdep.h" /* Always first... */ +#include <...> /* then system headers... */ +#include "..." /* and finally QEMU headers. */ + +The "qemu/osdep.h" header contains preprocessor macros that affect the behavior +of core system headers like . It must be the first include so that +core system headers included by external libraries get the preprocessor macros +that QEMU depends on. + 2. C types It should be common sense to use the right type, but we have collected