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Re: ping #3: [RFA] Add --with-libz-prefix option in config/zlib.m4
- From: Mark Wielaard <mjw at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Joel Brobecker <brobecker at adacore dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Binutils <binutils at sourceware dot org>, GDB <gdb-patches at sourceware dot org>
- Date: Thu, 19 Feb 2015 08:17:35 +0100
- Subject: Re: ping #3: [RFA] Add --with-libz-prefix option in config/zlib.m4
- Authentication-results: sourceware.org; auth=none
- References: <20150218120841 dot GD23529 at adacore dot com> <CAMe9rOp9YQrhwwrmqRa+a-04BNvd+p9_MVgxkiVhgt+6TkDb7g at mail dot gmail dot com> <20150218165457 dot GU544 at vapier> <CAMe9rOqVim3=-RCuWE6GnMKoQ1v9WKaDqfaS2k8MpDz7rA_y3g at mail dot gmail dot com> <20150218194443 dot GW544 at vapier> <CAMe9rOqB=zd21_q_C3OGVveza8-y44L2_VntsBZ=C=iBQaaDEA at mail dot gmail dot com> <1424291541 dot 23458 dot 28 dot camel at bordewijk dot wildebeest dot org> <CAMe9rOow3D--tayrR6y_qxoZqXZAZh4g0f9qo8Jd+hYdORRMJQ at mail dot gmail dot com> <1424295643 dot 23458 dot 30 dot camel at bordewijk dot wildebeest dot org> <CAMe9rOqwOa-kzOhaH_D84eGgYE0wV7k-J4jsxXUmHak4On_=aQ at mail dot gmail dot com>
On Wed, Feb 18, 2015 at 01:54:17PM -0800, H.J. Lu wrote:
> On Wed, Feb 18, 2015 at 1:40 PM, Mark Wielaard <firstname.lastname@example.org> wrote:
> > On Wed, 2015-02-18 at 12:53 -0800, H.J. Lu wrote:
> >> On Wed, Feb 18, 2015 at 12:32 PM, Mark Wielaard <email@example.com> wrote:
> >> > That doesn't seem like a smart default. And why is is Linux/x86 only?
> >> > Shouldn't that be something that is done explicitly by a distro
> >> > configuring binutils after making sure it actually is beneficial
> >> > (debuginfo is often compressed in a different way, on the package/file
> >> > level or with dwz). And after making sure all tools actually work with
> >> > it? There are various tools that don't handle the .zdebug format like
> >> > valgrind. And at least elfutils has trouble with it for ET_REL files,
> >> > like kernel modules, because relocations don't actually apply anymore to
> >> > the section data as is (but only after the decompression).
> >> Now it becomes a monthly topic:
> >> https://sourceware.org/ml/binutils/2015-01/msg00089.html
> > Thanks, I hadn't seen that before. Alan Modra makes some good points in
> > that thread why it is not a good change:
> > https://sourceware.org/ml/binutils/2015-01/msg00135.html
> > Do people agree with that? And/Or can the change be reverted for now
> > till there is agreement it is a desirable default?
> It may not be a good idea for all targets. If you find an issue
> on Linux/x86, please file a bug binutils report.
The issue is that this is not something that is target architecture
specific. As others have pointed out this isn't something that is
target architecture-dependent. So please first get agreement on whether
or not to default for the OS (or for all ELF targets or the GNU targets).
Otherwise distros will have to revert on a target by target basis to get
something consistent. Secondly the bug is not directly in binutils (but
there might be an issue between versions compiled with/without zlib
support). If .zdebug sections are left in on disk ET_REL files, like
kernel modules, there is a problem for programs that don't deal with
.zdebug sections (and/or relocations against them) in ET_REL files
like elfutils, systemtap, debugedit, dwz, etc.