[CentOS-devel] packaging DPDK 21.11 in RPM in CentOS 7 (elftools not found)

Fri Apr 29 12:03:24 UTC 2022
Josh Boyer <jwboyer at redhat.com>

On Fri, Apr 29, 2022 at 7:50 AM Stefan Puiu <stefan.puiu at gmail.com> wrote:
> Hi,
> I've already asked this on the dpdk-users list
> (https://mails.dpdk.org/archives/users/2022-April/006395.html) without
> getting any answer, so I thought maybe I'd also try centos-devel,
> since this is a CentOS and dpdk question.
> We're using a CentOS 7 based distro that is obviously RPM-based, and
> we package the DPDK with it, in order to run on some of our x86-64
> hardware boards. Now, we currently have DPDK 20.11 in our image and
> are looking to upgrade to 21.11, and I'm hitting a build error about
> elftools not being found:
> Program python3 found: YES (/usr/bin/python3)
> ../buildtools/meson.build:49:8: ERROR: Problem encountered: missing
> python module: elftools
> The fix seems to be to install pyelftools from pip:
> pip3 install pyelftools
> But that only works for building directly with meson / ninja. That
> doesn't work when building through rpmbuild. I've struggled to
> understand this, until I found this RedHat bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=1937494. It seems Fedora
> changed the python3 search path so that /usr/local/lib/python is not
> taken into account if RPM_BUILD_ROOT is defined (see
> https://fedoraproject.org/wiki/Changes/Making_sudo_pip_safe); so
> basically, when building with rpmbuild, pip-installed packages are
> ignored.
> I think I can understand the rationale of the Fedora change when you
> want to ensure that dependencies are properly set: packages installed
> using pip are not recorded as RPM dependencies, and the package might
> break at runtime. However, as far as I can tell, pyelftools seems to
> be a *build-time dependency*; removing the elftools check in the meson
> script leads to a build failure. There's no pyelftools RPM for CentOS
> 7
> that I could find, so I don't see another option than installing the package
> from pip. Also, the python change in Fedora doesn't seem to allow for
> any workaround. The only thing that I can think of is ugly as hell:
> symlink everything under /usr/local/python in /usr/lib/python for the
> DPDK build. I'm not even sure we need pyelftools at runtime; in our
> build of DPDK-20.11, dpdk-pmdinfo.py doesn't even run (because of
> missing pyelftools :) ).
> Are there any other people struggling with this? Is there any more
> elegant approach that I haven't thought of?

pyelftools is available in EPEL 7, but it's built for python2.
Looking at the spec file, it seems like it will build just fine for
python3, so you might be able to munge it and rebuild on your system
to have a python3-pyelftools RPM to install.