From owner-svn-src-all@freebsd.org Fri Aug 25 19:27:06 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C08E0DDFCF7; Fri, 25 Aug 2017 19:27:06 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from mail.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 961906DCA1; Fri, 25 Aug 2017 19:27:06 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from ralph.baldwin.cx (c-73-231-226-104.hsd1.ca.comcast.net [73.231.226.104]) by mail.baldwin.cx (Postfix) with ESMTPSA id 0457410AB01; Fri, 25 Aug 2017 15:27:05 -0400 (EDT) From: John Baldwin To: Warner Losh Cc: Ed Maste , Ryan Libby , "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , src-committers , "freebsd-toolchain@freebsd.org" Subject: Re: svn commit: r322824 - in head: lib/clang share/mk usr.bin/clang Date: Fri, 25 Aug 2017 11:53:59 -0700 Message-ID: <4019876.lu34otUPCV@ralph.baldwin.cx> User-Agent: KMail/4.14.10 (FreeBSD/11.1-STABLE; KDE/4.14.30; amd64; ; ) In-Reply-To: References: <201708232330.v7NNUPpV052276@repo.freebsd.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.4.3 (mail.baldwin.cx); Fri, 25 Aug 2017 15:27:05 -0400 (EDT) X-Virus-Scanned: clamav-milter 0.99.2 at mail.baldwin.cx X-Virus-Status: Clean X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 25 Aug 2017 19:27:06 -0000 On Friday, August 25, 2017 12:30:11 PM Warner Losh wrote: > On Fri, Aug 25, 2017 at 12:27 PM, Ed Maste wrote: > > > On 25 August 2017 at 14:07, Ryan Libby wrote: > > > On Wed, Aug 23, 2017 at 4:30 PM, John Baldwin wrote: > > >> Author: jhb > > >> Date: Wed Aug 23 23:30:25 2017 > > >> New Revision: 322824 > > >> URL: https://svnweb.freebsd.org/changeset/base/322824 > > >> > > >> Log: > > >> Improve the coverage of debug symbols for MK_DEBUG_FILES. > > >> > > ... > > > This causes llvm to emit hundreds of new warnings [1] for > > > "DWARF2 only supports one section per compilation unit" > > > > > > Are these expected? Are they a concern? Should we silence them? > > > Is this an upstream llvm bug [2]? > > > > I'm not sure they were "expected" but I guess are an unsurprising > > consequence of building more things with debug. In any case they're > > not a concern. > > > > It is an llvm bug (the warning really ought not be emitted for empty > > sections), but upstream is probably not too concerned as (most? all) > > other platforms are not using dwarf2. > > > > The right answer for us is likely to just stop defaulting to dwarf2 > > (and specifying it via CFLAGS for kernel if necessary). > > > > What's the status of kicking gdb out of the tree? If we kick it out, we can > stop doing dwarf2 and move to something more modern. Last time this issue > came up, that was the decision, pending a few issues with the gdb port > which I think John Baldwin is getting close to reaching closure on. gdb is mostly disabled in-tree, but there is no in-tree replacement for the kgdb stack trace from /usr/sbin/crashinfo if the gdb port is not installed, and there won't be until lldb grows some kernel support. OTOH, for most platforms /usr/bin/gdb is now disabled (hidden in /usr/libexec) so isn't relevant for userland binaries certainly. The kernel probably doesn't benefit much from DWARF > 2 (except perhaps for .dwo files if we decide to use those at some point) as the other things added since DWARF2 are largely about handling C++ features like r-value references, etc. -- John Baldwin