Excerpts from Adrian Bunk's message of 2019-10-29 22:18:21 +02:00: > On Wed, Oct 16, 2019 at 08:44:56AM +1000, Dan Callaghan wrote: > > Elfutils has optional support for bzip2 and xz (lzma). It uses > > this for decompressing embedded ELF sections like the .gnu_debugdata > > section for "mini debuginfo": > > > > https://sourceware.org/gdb/onlinedocs/gdb/MiniDebugInfo.html > >... > > +PACKAGECONFIG ??= "bzip2" > > +PACKAGECONFIG[bzip2] = "--with-bzlib,--without-bzlib,${DEPENDS_BZIP2}" > > +PACKAGECONFIG[xz] = "--with-lzma,--without-lzma,xz" > >... > > Is any tooling actually doing this compression by default? > > It is a bit surprising that this has the mostly-obsolete bzip2 enabled > by default but not the more common (and better compressing) xz.
I couldn't find anything that would ever use the bzip2 decompression in elfutils, so I had a quick look at why they even added bzip2 support in the first place. It turns out it was for reading compressed kernel images (presumably, in the elfutils tools like eu-readelf): https://sourceware.org/git/?p=elfutils.git;a=commitdiff;h=d6ccdc1a05f27bf0bb5d802ec14f879aa9fe3e98 commit d6ccdc1a05f27bf0bb5d802ec14f879aa9fe3e98 Author: Roland McGrath <rol...@redhat.com> Date: Wed Aug 26 00:23:01 2009 -0700 libdwfl: Support Linux bzip2 kernel images for automatic decompression. And indeed on my Fedora host eu-readelf can decode ELF information from a kernel bzImage, but the eu-readelf built by Yocto's elfutils-native recipe says "not a valid ELF file" when I feed it the same bzImage. Whether that's useful or not is a different question. In our product I am planning to disable bzip2 (because we don't use the elfutils tools for anything) and enable xz (for .gnu_debugdata sections). -- Dan Callaghan <dan.callag...@opengear.com> Software Engineer Opengear <https://opengear.com/>
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