Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751859AbWJIM15 (ORCPT ); Mon, 9 Oct 2006 08:27:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932571AbWJIM15 (ORCPT ); Mon, 9 Oct 2006 08:27:57 -0400 Received: from emailer.gwdg.de ([134.76.10.24]:37264 "EHLO emailer.gwdg.de") by vger.kernel.org with ESMTP id S1751859AbWJIM14 (ORCPT ); Mon, 9 Oct 2006 08:27:56 -0400 Date: Mon, 9 Oct 2006 14:20:26 +0200 (MEST) From: Jan Engelhardt To: Kyle Moffett cc: David Howells , Matthew Wilcox , torvalds@osdl.org, akpm@osdl.org, sfr@canb.auug.org.au, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH 1/4] LOG2: Implement a general integer log2 facility in the kernel [try #4] In-Reply-To: Message-ID: References: <20061006133414.9972.79007.stgit@warthog.cambridge.redhat.com> <20061006203919.GS2563@parisc-linux.org> <5267.1160381168@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Report: Content analysis: 0.0 points, 6.0 required _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1391 Lines: 43 >> > > > Were you planning on porting Linux to a machine with >> > > > non-8-bit-bytes any >> > > > time soon? Because there's a lot more to fix than this. >> > > >> > > I am considering the case [assuming 8-bit-byte machines] where >> > > sizeof(u32) is not 4. Though I suppose GCC will probably make a >> > > 32-bit >> > > type up if the hardware does not know one. >> > >> > If the machine has 8-bit bytes, how can sizeof(u32) be anything other >> > than 4? >> >> typedef unsigned int u32; >> >> Though this should not be seen in the linux kernel. > > Well, uhh, actually... > > All presently-supported architectures do exactly that. Well, some do: > > typedef unsigned int __u32; > #ifdef __KERNEL__ > typedef __u32 u32; > #endif Ouch ouch ouch. It should better be typedef uint32_t __u32; So that even if there happens to be a compiler that does sizeof(int)=8, sizeof(u32) will actually be 4. Say, if there happens to be an architecture that does only know 64-bit integers, the compiler will have some extra magic to make uint32_t behave like a 32-bit type in C and transparently use 64-bit assembler. So far the theory. -`J' -- - 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/