Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758049AbZFIGyT (ORCPT ); Tue, 9 Jun 2009 02:54:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753844AbZFIGyJ (ORCPT ); Tue, 9 Jun 2009 02:54:09 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:51307 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753918AbZFIGyI (ORCPT ); Tue, 9 Jun 2009 02:54:08 -0400 Date: Tue, 9 Jun 2009 08:53:50 +0200 From: Ingo Molnar To: Paul Mackerras Cc: Peter Zijlstra , Arnaldo Carvalho de Melo , Thomas Gleixner , Corey Ashford , linux-kernel Subject: Re: [PATCH] perf_counter: extensible perf_counter_attr Message-ID: <20090609065350.GB16707@elte.hu> References: <1244481941.13761.9119.camel@twins> <18989.57919.895309.847520@drongo.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18989.57919.895309.847520@drongo.ozlabs.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1121 Lines: 36 * Paul Mackerras wrote: > Peter Zijlstra writes: > > > Allow extending the perf_counter_attr structure by linking extended > > structures to it. > > ... > > > @@ -175,6 +175,13 @@ struct perf_counter_attr { > > __u32 __reserved_3; > > > > __u64 __reserved_4; > > + > > + struct perf_counter_attr_ext *ext_attrs; > > +}; > > Since this is a user-visible structure, you've just introduced an > ABI difference between 32-bit and 64-bit processes, which we've > managed to avoid so far. [...] This is a good point too - handling pointers in ABIs is possible but should be avoided as much as possible: it creates the need to introduce a compat_sys_perf_counter_open() and doubles the syscall table complexity. Lets do the s/__reserved_1/attr_size ABI i suggested (i outlined various properties of it in the previous mail). Agreed? Ingo -- 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/