Re: ctfconvert: rc = 1 Unsupported version [_dwarf_info_load(229)]

On Fri, Nov 26, 2021 at 02:48:03PM -0500, Mark Johnston wrote:
> On Fri, Nov 26, 2021 at 02:00:27PM -0500, Mark Johnston wrote:
> > On Fri, Nov 26, 2021 at 06:12:49PM +0200, Andriy Gapon wrote:
> > > On 26/11/2021 18:06, Mark Johnston wrote:
> > > > On Thu, Nov 25, 2021 at 10:48:36PM +0200, Andriy Gapon wrote:
> > > >>
> > > >> I've just finished builds of yesterday's CURRENT / main for arm and arm64.
> > > >> In both builds I got lots of messages from ctfconvert:
> > > >>     ctfconvert: rc = 1 Unsupported version [_dwarf_info_load(229)]
> > > >>
> > > >> I got an impression that there was a message for each object file, that's how
> > > >> many of them were there.
> > > >>
> > > >> I don't recall seeing those messages before.
> > > >>
> > > >> Should I be concerned?
> > > >> Maybe I am doing something wrong or have an unusual configuration?
> > > >> Any way to fix the issue?
> > > >>
> > > >> Thanks!
> > > >>
> > > >> P.S.
> > > >> The builds were done on stable/13, so maybe there is an issue with host tools
> > > >> not being able to grok something new.
> > > > 
> > > > I haven't seen this before, for what it's worth.  I presume this is from
> > > > a kernel build?  Does the configuration enable generation of debug info
> > > > with, e.g., "makeoptions DEBUG=-g"?
> > > 
> > > This is actually from buildworld.
> > > buildkernel is silent.
> > 
> > Thanks, I can reproduce it now.
> > 
> > Our libdwarf is complaining that the first compilation unit header in
> > .debug_info contains an unsupported DWARF version number (libdwarf only
> > supports 2, 3 and 4).  In files compiled by clang it ends up being zero.
> > For instance, compiling bin/cat and dumping the .debug_info section:
> > 
> > gcc10:
> >  c1250000 04000000 00000801 00000000
> >            ^ DWARF version
> > clang:
> >   01000000 00000000 4e230000 00000000
> > 
> > llvm-dwarfdump and binutils readelf are somehow still able to find a
> > valid-looking unit header, but I haven't yet been able to figure out how
> > they do that from reading the DWARF 4/5 specs or the LLVM sources.
> 
> Ah, we recently started configuring clang to compress debug sections by
> default, and our libdwarf doesn't know how to handle that.  As an
> interim workaround this could simply be disabled with WITH_CTF is
> configured:

... or give this a try: https://reviews.freebsd.org/D33139