Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755343AbbHZNcl (ORCPT ); Wed, 26 Aug 2015 09:32:41 -0400 Received: from mail.kernel.org ([198.145.29.136]:48629 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751275AbbHZNck (ORCPT ); Wed, 26 Aug 2015 09:32:40 -0400 Date: Wed, 26 Aug 2015 10:32:35 -0300 From: Arnaldo Carvalho de Melo To: "Wangnan (F)" Cc: =?utf-8?B?5bmz5p2+6ZuF5bezIC8gSElSQU1BVFXvvIxNQVNBTUk=?= , "mingo@redhat.com" , "namhyung@kernel.org" , "pi3orama@163.com" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] perf probe: Support probing at absolute address Message-ID: <20150826133235.GA18596@kernel.org> References: <1440509256-193590-1-git-send-email-wangnan0@huawei.com> <1440509256-193590-2-git-send-email-wangnan0@huawei.com> <50399556C9727B4D88A595C8584AAB37524EA491@GSjpTKYDCembx32.service.hitachi.net> <55DD269A.7030408@huawei.com> <20150826130223.GN19203@kernel.org> <55DDBCDF.8050607@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <55DDBCDF.8050607@huawei.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1938 Lines: 41 Em Wed, Aug 26, 2015 at 09:19:27PM +0800, Wangnan (F) escreveu: > On 2015/8/26 21:02, acme@kernel.org wrote: > >Em Wed, Aug 26, 2015 at 10:38:18AM +0800, Wangnan (F) escreveu: > >>On 2015/8/26 8:02, 平松雅巳 / HIRAMATU，MASAMI wrote: > >>>>From: Wang Nan [mailto:wangnan0@huawei.com] > >>>> # perf probe /lib/x86_64-linux-gnu/libc-2.19.so +0xeb860 > >>>Why do we need "+" for the absolute address? > >>>It seems that we can do it if we find that the given probe point > >>>starts with "0x". > >>I will change 2/2 as you suggestion. > >>However, we can only ensure that in kernel side symbol never leading > >>with '0x'. Although I don't think symbol leading with 0x is useful, > >>it is still possible for a userspace program compiled and linked by > >>a language other than C produces such symbol. '+' helps us separate > >>address and function name semantically, make us don't rely on assumption > >>on function names. If in future we do meet '0x' symbols, I think we still > >>need the '+' syntax back. But we can do it at that time. > >Agreed, I also think that using '+' is better, but will not dwell on > >this so as to make progress :-) > Maybe we should support both of them, making '+0x1234' the core > syntax, and '0x1234' style as a syntax sugar. However I have worked > on this problem for nearly a full day but my main work should be BPF > related things... > Since Masami has acked all of the 6 v3 patches, if we still need '+' I can > bring it back with a new patch when I have time. However, same to you, > I don't think this should be a blocking problem. Agreed, we don't have to agree on everything all the time, lets keep Masami happy this time :-) - Arnaldo -- 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/