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 5F6B620FA86 for ; Tue, 29 Oct 2024 23:50:28 +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=1730245828; cv=none; b=b7vDvOy+IzljisI8QpDE5stx3CzL4nV6ftGqZ0x8ySUjpAebEYZAnwgH7UH6XteF9AnxhSho3Luhkpar/8Fzu5cV5XOyvuPNFmlu9iZhpbeK0THFXn0iLdWNIJBZ5T21+DPiNSMVbfOdXpqkqUCHr0e/9busektDuvTW6zFsc88= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730245828; c=relaxed/simple; bh=Km9QmhwRo6fGnvgC/ifviJ2aCCdQhRE1CmRblF85asg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QZN5bWEKioRg4DOprLEK0vlMWIOt5XkHAmNCrhZLR9dPIORexelp9uafhiZWXwdygwNRbXd5b1Z0IIHzljmQ4wznwTkRs7kwlfIVJvZFu+iYAM0xSOK9v72P6/PTGGmduhImzJaHwdALiJWVPOORJVbwhYSSa6OGIJrzPH88hoc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JC+2IZMk; 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="JC+2IZMk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEA31C4CEEA; Tue, 29 Oct 2024 23:50:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730245828; bh=Km9QmhwRo6fGnvgC/ifviJ2aCCdQhRE1CmRblF85asg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JC+2IZMkf2PtwUS1yY44nzOEiCDiHphebj+axO+aS3IxTCiSsjv5N1JXcrYWBZCwD YTTnTA7tIUCg6gLt8hQmYAEVOscvdGKRnihq+CKB0gDPj1qLRP62iFWX7iTyojb7lL 82MaeQ6ZgqkB2nAAq7Z9d0pJDX47tryK6b/zcL5kigT+5vN5xUP6lbv0KgBd7D55op Evt5P+IRXUnD9sOvwoRskBz8XhTaQC2h0vKzBOHai1j6nMHUsiVZA5WB267J23zke2 ts1ojLLXgwItXxGszMXxyunwAP1y8iNkqPskLhPwfLg8J+pDnfFT6V3nalAolDHow8 i2LNXXA0k/Q8A== Date: Tue, 29 Oct 2024 16:50:26 -0700 From: Namhyung Kim To: Ian Rogers Cc: linux-perf-users , Arnaldo Carvalho de Melo , 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=utf-8 Content-Disposition: inline In-Reply-To: Hi Ian, 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? > > Possible savings: > - remove libunwind's 8 feature tests > - removal of 10 arch or not libunwind C files in perf > - removal of libunwind #ifdef-ed code throughout common files. I'm ok with removing libunwind to reduce the maintenance burden. In general, we'd better not have multiple libraries for the same purpose. Recently we added libllvm support, then it might replace libelf, libdw and libcapstone someday. :) Thanks, Namhyung