Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932555AbWLLW5j (ORCPT ); Tue, 12 Dec 2006 17:57:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932557AbWLLW5j (ORCPT ); Tue, 12 Dec 2006 17:57:39 -0500 Received: from smtp.osdl.org ([65.172.181.25]:54156 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932555AbWLLW5i (ORCPT ); Tue, 12 Dec 2006 17:57:38 -0500 Date: Tue, 12 Dec 2006 14:57:05 -0800 (PST) From: Linus Torvalds To: Benjamin Herrenschmidt cc: Kyle Moffett , LKML Kernel , Andrew Morton Subject: Re: Mach-O binary format support and Darwin syscall personality [Was: uts banner changes] In-Reply-To: <1165963139.11914.93.camel@localhost.localdomain> Message-ID: References: <457D750C.9060807@shadowen.org> <20061211163333.GA17947@aepfle.de> <20061211180414.GA18833@aepfle.de> <20061211181813.GB18963@aepfle.de> <320BD259-74D6-411F-82A4-4BF3CB15012F@mac.com> <0B8F288E-4FCD-409E-9BA2-C524CF31E9A3@mac.com> <1165963139.11914.93.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1273 Lines: 31 On Wed, 13 Dec 2006, Benjamin Herrenschmidt wrote: > > > Secondly, is there a preferred existing field into which I should > > stick said flag or just stuff it somewhere? > > Yes, thread_info->flags. Well, it may actually make sense to actually stick the whole "syscall table pointer" in there, rather than a flag that says which pointer to choose. We already load the thread_info pointer because we need the flags for syscall tracing, and since we have the thread_info pointer, it might be easier to load the syscall table pointer right off there, rather than loading it as a big constant with "lis + ori" (in fact, on ppc64, we currently load it off the TOC, which is really sad, since we already brought in the thread_info into the cache, and usign the TOC is not just a load, it's a load off a separate cacheline). So on 64-bit ppc, it could actually speed things up to put the system call table pointer into thread_info, and make it more flexible at the same time, without any conditional flags. Linus - 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/