Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754101Ab0ARMBs (ORCPT ); Mon, 18 Jan 2010 07:01:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751699Ab0ARMBr (ORCPT ); Mon, 18 Jan 2010 07:01:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:14590 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575Ab0ARMBr (ORCPT ); Mon, 18 Jan 2010 07:01:47 -0500 Message-ID: <4B544D7C.2060708@redhat.com> Date: Mon, 18 Jan 2010 14:01:00 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 MIME-Version: 1.0 To: Peter Zijlstra CC: ananth@in.ibm.com, Jim Keniston , Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , utrace-devel , Frederic Weisbecker , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) References: <20100111122521.22050.3654.sendpatchset@srikar.in.ibm.com> <20100111122529.22050.32596.sendpatchset@srikar.in.ibm.com> <1263467289.4244.288.camel@laptop> <1263498366.4875.25.camel@localhost.localdomain> <1263546228.4244.343.camel@laptop> <20100115093831.GC26396@in.ibm.com> <1263549014.4244.374.camel@laptop> <4B53213C.9050303@redhat.com> <1263739939.557.20938.camel@twins> <4B5325CF.5000001@redhat.com> <1263740593.557.20967.camel@twins> <4B53661A.9090907@redhat.com> <1263800752.4283.19.camel@laptop> <4B543F93.3060509@redhat.com> <1263815072.4283.305.camel@laptop> In-Reply-To: <1263815072.4283.305.camel@laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1284 Lines: 32 On 01/18/2010 01:44 PM, Peter Zijlstra wrote: > On Mon, 2010-01-18 at 13:01 +0200, Avi Kivity wrote: > >> You've made it clear that you don't like it, but not why. >> >> The kernel already manages the user's address space (except for >> MAP_FIXED which is unreliable unless you've already reserved the address >> space). I don't see why adding a vma for debugging is so horrible. >> > Well, the kernel only does what the user (and loader) tell it through > mmap(). What I meant was that the kernel chooses the addresses (unless you go the MAP_FIXED way). From the user's point of view, there is no change in behaviour: the kernel picks an address. If the constraints have changed (because we reserve a range), that doesn't affect the user. > Other than that we never (except this VDSO thing) inject vmas, > and I see no reason to start doing that now. > Maybe you place no value on uprobes. But people who debug userspace likely will see a reason. -- error compiling committee.c: too many arguments to function -- 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/