Re: ping #3: [RFA] Add --with-libz-prefix option in config/zlib.m4

Mark Wielaard
2015-02-18T20:32:31Z

On Wed, 2015-02-18 at 11:52 -0800, H.J. Lu wrote:
> On Wed, Feb 18, 2015 at 11:44 AM, Mike Frysinger <vapier@gentoo.org> wrote:
> > On 18 Feb 2015 08:58, H.J. Lu wrote:
> >> On Wed, Feb 18, 2015 at 8:54 AM, Mike Frysinger wrote:
> >> >> Why do you want to turn off zlib? On Linux/x86, zlib is required
> >> >> for assembler. At least, you should issue an error when --without-libz
> >> >> is used in binutils for Linux/x86 target.
> >> >
> >> > err, when did that happen ? why would zlib be possibly required for an
> >> > assembler ?
> >>
> >> commit 89e7505fcde4bd83948f559f429a0e1eb4262f05
> >> Author: H.J. Lu <hjl.tools@gmail.com>
> >> Date: Sun Dec 14 06:41:03 2014 -0800
> >>
> >> Compress debug sections for Linux/x86 by default
> >>
> >> * config/tc-i386.c (flag_compress_debug): Default to compress
> >> debug sections for Linux.
> >
> > i don't see how that justifies making it a hard requirement
>
> Can you elaborate?

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).

Cheers,

Mark