From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Jones Subject: Re: [PATCH] perf tools: update docs regarding kernel/user space unwinding Date: Fri, 27 Mar 2020 13:09:34 -0700 Message-ID: <20200327200934.GB2715@suse.de> References: <20200325164053.10177-1-tonyj@suse.de> <38ba2caa-dadd-52c4-c6ea-5e01b7e59ee2@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <38ba2caa-dadd-52c4-c6ea-5e01b7e59ee2@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: Paul Clarke Cc: linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org List-Id: linux-perf-users.vger.kernel.org On Thu, Mar 26, 2020 at 04:32:26PM -0500, Paul Clarke wrote: > > + and 'lbr'. The value 'dwarf' is effective only if libunwind > > + (or a recent version of libdw) is present on the system; > > + the value 'lbr' only works for certain cpus. The method for > > + kernel space is controlled not by this option but by the > > + kernel config (CONFIG_UNWINDER_*). > > Your changes are just copying the old text, so this isn't a criticism of your patches. > > Do we have information to replace "a recent version of libdw", which will quickly get stale? Hi Paul. The original "(libunwind or a recent version of libdw)" text was from Feb 2016. So a while ago. bd0419e2a5a9f requires >= 0.157 but this is for probing. 0a4f2b6a3ba50 specifies >= 0.158 but I see no mention of why in the commit but since it's from 2014 and elfutils is now at 0.178, I think it's safe to just remove the reference. As an aside, there is a lot of detail in perf-config.txt that's available in some of the other subcomands help files. Seems a good way for things to get stale. It could also do with some grammatical cleanup. Tony