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nerves-networking / vintage_net_wifi

WiFi networking for VintageNet
Apache License 2.0
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pkg-config undefined symbol: pkgconf_pkg_dir_list_build #66

Closed Bryan-Turek closed 2 years ago

Bryan-Turek commented 3 years ago

Hi,

I'm currently working on a nerves project that incorporates vintage_net_wifi within a custom nerves system layer. I ran into a unique issue where pkg-config appeared to unable to find a symbol that it was able to find when ran manually. In the Makefile the command $(shell /usr/bin/pkg-config --cflags libnl-genl-3.0) failed to return a valid path to the libnl3 header files. It appears the environment that was executing pkg-config was unable to locate '.so' file that contains the 'pkgconf_pkg_dir_list_build' symbol to successfully run. Through debugging, I was able to determine that $PKG_CONFIG was already set, presumably by the nerves platform, and was able to work-around the issue by removing line 51 in the Makefile: PKG_CONFIG = $(shell which pkg-config).

I've come to the conclusion that my development environment / configuration is not setup properly, though I've been unable to locate any configuration or setting that would resolve this issue. Especially considering I was able to get it to successfully build once. Any ideas?

fhunleth commented 3 years ago

I believe that the Makefile could be improved, but that doesn't explain why this works for me. What distribution of Linux are you using? Also, do you see the same issue with vintage_net_wifi when building against an official Nerves system?

Bryan-Turek commented 3 years ago

/etc/redhat-release: CentOS Stream release 8

I had attempted to use an official release, but have version 23 of the Erlang OTP installed. I had stopped once I encountered the version mismatch between host/target. My custom system was branched from an official release that worked previously and on another development environment (mac osx), and with very little changes, I believed that it shouldn't have had an effect on the vintage_net_wifi build (mostly partitioning changes). That being said, I will install asdf and swap between installed erlang versions to see if I can rebuild a hello_nerves application with vintage_net_wifi and see where that gets me.

fhunleth commented 3 years ago

I'm tempted to adjust the Makefile to check if $PKG_CONFIG is already set, since if it is, then the Makefile really should use it.

If you're comfortable making this change, please send a PR. If not, I'll look into making it in the morning (it's getting late here).

Bryan-Turek commented 3 years ago

I'm comfortable with submitting a PR, although i really feel like I am missing something. Mainly because:

  1. It had previously compiled before on the same development environment, but I had been switching between dev/prod MIX_ENVs. Or at least I believe it had, as I copied the entire source including (_build/deps) to the Linux environment before I cleaned up the builds.
  2. Seems like pkg-config should operate properly inside the Nerves system environment, although clearly doesn't in my case. Is the Nerves platform not behaving as intended in my environment? Ultimately, what is the desired outcome of which pkg-config inside the Makefile within the Nerves environment? should It be pointing to /usr/bin/pkg-config, or ~/.nerves/artifacts/custom_system-portable-X.X.X/host/usr/bin/pkg-config?
fhunleth commented 3 years ago

I had thought that both /usr/bin/pkg-config and ~/.nerves/artifacts/custom_system-portable-X.X.X/host/usr/bin/pkg-config should work the same and it shouldn't matter. Could there be a PKG_CONFIG environment variable already set in your .bashrc? Or perhaps there's a default built into /usr/bin/pkg-config that's not being overridden by Nerves to set the search paths appropriately?

ejc123 commented 2 years ago

I just had a similar problem with pkg-config; In this case /usr/bin/pkg-config: symbol lookup error: /usr/bin/pkg-config: undefined symbol: pkgconf_cross_personality_deinit I tracked it down to, as noted above, using /usr/bin/pkg-config vs. ~/.nerves/artifacts/custom_system-portable-X.X.X/host/usr/bin/pkg-config.
Further digging showed that it was being dynamically linked against ~/.nerves/artifacts/custom_system-portable-X.X.X/host/usr/lib/libpkgconf.so.3 Since my system pkg-config is 1.8.0 and the buildroot pkg-config is 1.6.3, this did not work. I have a Makefile patch that makes it use /usr/bin/pkg-config vs. ~/.nerves/artifacts/custom_system-portable-X.X.X/host/usr/bin/pkg-config

fhunleth commented 2 years ago

@ejc123 Do you have any idea why /usr/bin/pkg-config is being dynamically linked to ~/.nerves/artifacts/custom_system-..../host/usr/lib/libpkgconf.so.3? Rather than /usr/lib/libpkgconf.so.3?

ejc123 commented 2 years ago

LD_LIBRARY_PATH is being set to ~/.nerves/artifacts/custom_rpi0-portable-1.18.0-dev/host/usr/lib when I build with the custom Nerves system. When I build with the downloaded rpi0 target, LD_LIBRARY_PATH is empty.

fhunleth commented 2 years ago

Thanks for looking into this more.

Could you confirm that ~/.nerves/artifacts/custom_rpi0-portable-1.18.0-dev/host/usr/bin is in your $PATH and before your system paths? It is for me, and I'd think that would make the pkg-config in the custom Nerves system get found.

My other thought is that the code that adds the host directories to your $PATH and $LD_LIBRARY_PATH could be deleted completely. That would make using a custom system during development more similar to using it after it's been released. I'm highly leaning towards doing this, but I wanted to verify that something else wasn't going on.

ejc123 commented 2 years ago

Whatever is adding ~/.nerves/artifacts/custom_rpi0-portable-1.18.0-dev/host/usr/bin to my $PATH is adding it at the end.
What part of the code is responsible for adding these to $PATH and $LD_LIBRARY_PATH ?

fhunleth commented 2 years ago

I changed the code to add the path is in the first commit in https://github.com/nerves-networking/vintage_net_wifi/issues/66. I don't use this, though, so could you verify that I did it right?

@jjcarstens - I may need your assistance if this doesn't work.

ejc123 commented 2 years ago

I verified that this change allows it to build; $PATH has ~/.nerves/artifacts/custom_rpi0-portable-1.18.0-dev/host/bin as the first entry and $PKG_CONFIG is ~/.nerves/artifacts/custom_rpi0-portable-1.18.0-dev/host/bin/pkg-config

fhunleth commented 2 years ago

Great! Thanks for debugging and verifying the fix. I'd like to get another change in nerves_system_br before the next release, but hopefully that won't take too long.