Cross compiling

[timglong]

Instead of building librespot directly on my Pi4, @pejobo suggested in #1623 that I might want to try cross compiling instead (thanks!). I figured I would give it a shot, so I followed the instructions in COMPILING.md, installed Docker, and then followed the cross compiling instructions. Everything seemed to work as intended, and I ended up with the expected folders in /tmp/librespot-build/. Great!

Unfortunately at this point I'm not sure what to do next, and/or what I'm doing wrong. I tried copying the aarch64 binary to my Pi4 and using it the same way I use the binary created after running cargo install librespot, but this didn't work (after cargo install finishes, I copy the binary to /usr/local/bin/ and set permissions so snapserver can access it). I ran cargo install librespot on the Pi directly and everything worked as usual.

I imagine I'm missing something simple or obvious, but I'm not sure what. Any help would be greatly appreciated!

I'm also wondering whether it was necessary to follow the COMPILING.md instructions before running the Docker commands for cross compiling. I assumed so, but I wasn't sure.

If I can get this working, I'm happy to write up the steps I took. It was quite a bit faster to compile librespot on my desktop vs. the Pi4, though it only takes about 20 minutes on the Pi, which I don't mind.

[michaelherger]

Did you also set the executable flag on the binary (chmod a+x librespot)? What happens if you try to run the binary directly?

[timglong]

Ah interesting, I did make it executable, so that wasn't the problem, but running it directly gave me the following error:

/lib/aarch64-linux-gnu/libc.so.6: version 'GLIBC_2.39' not found (required by ./librespot)

I should have tried running it directly, thanks for that!

I see some previous issues that appear similar (like #142 and #1263); based on these it seems like it should be as simple as modifying the Dockerfile to debian:bookworm (edit: bookworm, not buster, lol) and re-compiling. I'll give that a shot later today and report back.

[timglong]

I think this also answers my question about whether I needed to install Rust locally. Everything should be handled by Docker, I think, making a local Rust installation unnecessary.

[timglong]

This worked! It was slightly more complicated than simply changing FROM: debian:trixie to FROM debian:bookworm, but only slightly.

Here are the steps I took:

1. docker system prune --volumes This is the only Docker-related thing on this machine and I wanted to ensure the previous compiling didn't mess anything up. See here for more info.
2. Modified the Dockerfile:
   a. Changed FROM: debian:trixie to FROM debian:bookworm
   b. Commented out the rustup part of the initial dependencies installation, as installing via apt doesn't work prior to trixie.
   c. Added RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y to get rustup installed. Note the addition to make the installation non-interactive; this was helpful.
3. Ran the cross compiling Docker commands. Everything worked!

Moved the binary to my Pi4, set permissions, everything works. Thanks for the help @michaelherger !