Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755169AbZGXXGh (ORCPT ); Fri, 24 Jul 2009 19:06:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754896AbZGXXGh (ORCPT ); Fri, 24 Jul 2009 19:06:37 -0400 Received: from lazybastard.de ([212.112.238.170]:37915 "EHLO longford.logfs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751899AbZGXXGg (ORCPT ); Fri, 24 Jul 2009 19:06:36 -0400 Date: Sat, 25 Jul 2009 01:06:20 +0200 From: =?utf-8?B?SsO2cm4=?= Engel To: Stephen Hemminger Cc: Arnd Bergmann , virtualization@lists.linux-foundation.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, virtualization@lists.osdl.org, Sam Ramji , Haiyang Zhang , Hank Janssen Subject: Re: [patch 34/54] Staging: hv: remove STRUCT_PACKED and STRUCT_ALIGNED defines Message-ID: <20090724230619.GB13702@logfs.org> References: <20090717180850.873962925@mini.kroah.org> <20090717180921.448023599@mini.kroah.org> <200907210146.41399.arnd@arndb.de> <20090724213218.GA13702@logfs.org> <20090724145025.12da5a6e@nehalam> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20090724145025.12da5a6e@nehalam> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1251 Lines: 30 On Fri, 24 July 2009 14:50:25 -0700, Stephen Hemminger wrote: > On Fri, 24 Jul 2009 23:32:19 +0200 > Jörn Engel wrote: > > > On Tue, 21 July 2009 01:46:41 +0200, Arnd Bergmann wrote: > > > > > > The data structure is actually packed already, the attribute does not make it better > > > and could be removed. We also have __packed as a shortcut for __attribute__((packed)). > > > > Honestly, I don't know how useful __packed really is. In a shared > > kernel/userspace header, it is only defined for the kernel. > > As I remember, gcc generates worse code for packed structures on many architectures > since it may have to do byte fetchs/recombining to avoid unaligned > accesses. I was talking about "__packed" vs. "__attribute__((packed))". But yes, avoiding packed structures where possible is a good idea. Jörn -- "[One] doesn't need to know [...] how to cause a headache in order to take an aspirin." -- Scott Culp, Manager of the Microsoft Security Response Center, 2001 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/