From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C0BA513AD11 for ; Mon, 28 Oct 2024 17:01:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730134881; cv=none; b=l/fEFmA5rtDVFQLHT5YJdDzpRLhs+txtDtm1+W5bismp0IdsGq5jTpH272T7NaOAYnr/DhYFUt++Qk6kDdiUj10tdCQsfCKBe90YWUXmNkMsVUS/KITzEsHaXWx0vEamKZmnsV9GStTTnTNVVMiXJ14omz95Dso6lXX1rO8mLFk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730134881; c=relaxed/simple; bh=kdGCNGPFrHbBc21gfZLuHiW9sHHvBjXh5uK9c2elIgg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MHR9vcuSpik1uhEfE0f3utOaC9rrO+5gWrY8T4vnfq8AkLPUiStChNz/IOTCqWCVUROIUmHbK7/TX/tcMvD7JJU80hAE+sb1BFNo8wpmqVPoADe7J9GUXwKBxh8bPLJGytjnkJyVcpSNoPK5POXYDBnvSpbzqpx9brPxxxqxoWY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CkbNb8iJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CkbNb8iJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1047C4CEC3; Mon, 28 Oct 2024 17:01:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730134881; bh=kdGCNGPFrHbBc21gfZLuHiW9sHHvBjXh5uK9c2elIgg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CkbNb8iJmYkNl59w/brnZYB2wo0HfgSPOsgkZrmSasdz2MHcB1CHoMv32bvF7aehU Ycv0jXIng7cUWqR5dM6mApJcW5/88zNO2p9Vck18l9brBRYlSNYebVTeZXxMm9Bdi3 B5tFJhSfSQEc5kZ+H13M9Px4/jghSMAHIWkT9a9YImrXewjcbM+aJTYVa1P+S7bZFe T95jA2qjw9V78+iP7LfOEJWv1b8F7LdqJ3eQtMzvI65lgmqExV5RLbLcIuV+YKByw3 Pdnd0Y83eN/S/MkGlTQ58P3WfH8nntoYE0DUxgpixdy7ISsbDcTnuzhFTgMIcIKqeh modWptDPzi40w== Date: Mon, 28 Oct 2024 18:01:18 +0100 From: Frederic Weisbecker To: Arnaldo Carvalho de Melo Cc: Ian Rogers , linux-perf-users , Namhyung Kim , Masami Hiramatsu , Jiri Olsa , Adrian Hunter Subject: Re: Can perf drop libunwind support Message-ID: References: Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Le Mon, Oct 28, 2024 at 01:03:03PM -0300, Arnaldo Carvalho de Melo a écrit : > On Wed, Oct 23, 2024 at 02:57:05PM -0700, Ian Rogers wrote: > > Hi, > > > > perf wants to build with BPF support these days. libbpf has a > > dependency on libelf, part of elfutils. libdw is also part of elfutils > > and amongst other things provides unwinding support. My understanding > > is libdw unwinding is used by perf in preference to libunwind when > > present. My suspicion is that libunwind is being feature tested, > > linked against but then seldom or never used. Given this could perf > > drop libunwind support in order to simplify the code base? > > Probably Jiri remembers the reasons for us to have support for both, > IIRC libunwind was a bit more mature at the time and so we decided to > have both and when some broken behaviour appears we try the other one, > in the process trying to fix the one wioth a problem? > > Adding Frederic as well, this is when we started to use libunwind: Ouch, memories are blurry... It's possible that libdw deprecated libunwind at some point. I'm sorry I completely lost track of these things since then :-s thanks.