Will you consider supporting it on Android?

[editso]

Hi, I tried to build for Android, but the build failed. Does it support Android? If possible, can I create a PR to support it?

[alexforster]

Hi – sounds fine theoretically, but I don't know anything about Android development. Does it mean adding lots of Android-specific build system stuff?

[editso]

Hi – sounds fine theoretically, but I don't know anything about Android development. Does it mean adding lots of Android-specific build system stuff?
The main thing here is to solve the compilation of elfutils. On Android, it lacks some related macros. You only need to solve these problems. I referred to aosp/elfutils At this point, I successfully built for Android

[amirbou]

Hey, bumping this issue :)
I'm really hopeful we can think of a proper solution, so I'm listing my thoughts on the manner.
This is also relevant for libbpf/libbpf-rs#267

I personally managed to make it compile by specifying:

[target.aarch64-linux-android.libbpf]
rustc-link-lib = ["static=bpf", "static=elf", "z"]

[target.x86_64-linux-android.libbpf]
rustc-link-lib = ["static=bpf", "static=elf", "z"]

in my .cargo/config.toml, and compiling libelf and libbpf myself (as submodules) using make,
which is pretty annoying.

The main issues I had to solve:

• config.toml should point to a valid NDK (Android's cross compile toolchains)
  • This should already be the case for anyone trying to compile for Android
  • It might be difficult to determine the "Minimum Supported NDK Version"
• It's hard to build elfutils for Android
  • As @editso mentioned, AOSP contains a fork of the library (https://android.googlesource.com/platform/external/elfutils/), that builds only libelf, with some Android specific patches (see Android.bp and bionic-fixup/), using the Soong build system
  • libbpf-bootstrap uses XMake (at least for C examples), which pulls libbpf using https://github.com/xmake-io/xmake-repo/blob/dev/packages/l/libbpf/xmake.lua if the "system-libbpf" configuration is specified.
    It uses both elfutils and libelf (which doesn't seem to be actively maintained), and also requires building libintl and argp-standalone when targeting Android

It seems to me that there are 3 possible solutions:

1. Maintain libelf, libintl and argp-standalone as submodules and build them when targeting Android
2. Maintain a set of patches to elfutils to make it compile only libelf, without the need of libintl and argp (that's what I did in my personal project)
3. Use XMake to build the necessary libraries when targeting Android

IMHO the last solution would be the most reasonable one, and it can also be gated behind a crate feature to not interfere with "normal" builds

I'll try to work on a PR to see if there is anything that I missed.

I'd like to hear your thoughts on the idea :)

[editso]

Hey, bumping this issue :) I'm really hopeful we can think of a proper solution, so I'm listing my thoughts on the manner. This is also relevant for libbpf/libbpf-rs#267

I personally managed to make it compile by specifying:

[target.aarch64-linux-android.libbpf]
rustc-link-lib = ["static=bpf", "static=elf", "z"]

[target.x86_64-linux-android.libbpf]
rustc-link-lib = ["static=bpf", "static=elf", "z"]

in my .cargo/config.toml, and compiling libelf and libbpf myself (as submodules) using make, which is pretty annoying.

The main issues I had to solve:

• config.toml should point to a valid NDK (Android's cross compile toolchains)

  • This should already be the case for anyone trying to compile for Android
  • It might be difficult to determine the "Minimum Supported NDK Version"

• It's hard to build elfutils for Android

  • As @editso mentioned, AOSP contains a fork of the library (https://android.googlesource.com/platform/external/elfutils/), that builds only libelf, with some Android specific patches (see Android.bp and bionic-fixup/), using the Soong build system
  • libbpf-bootstrap uses XMake (at least for C examples), which pulls libbpf using https://github.com/xmake-io/xmake-repo/blob/dev/packages/l/libbpf/xmake.lua if the "system-libbpf" configuration is specified.
    It uses both elfutils and libelf (which doesn't seem to be actively maintained), and also requires building libintl and argp-standalone when targeting Android

It seems to me that there are 3 possible solutions:

1. Maintain libelf, libintl and argp-standalone as submodules and build them when targeting Android
2. Maintain a set of patches to elfutils to make it compile only libelf, without the need of libintl and argp (that's what I did in my personal project)
3. Use XMake to build the necessary libraries when targeting Android

IMHO the last solution would be the most reasonable one, and it can also be gated behind a crate feature to not interfere with "normal" builds

I'll try to work on a PR to see if there is anything that I missed.

I'd like to hear your thoughts on the idea :)

My approach was just to add the missing macros and some header files, then it started working.

[amirbou]

That's awesome!
It seems like configure is only used to produce the config.h file, and then you compile the library yourself without make,
did you have any issues with config.h producing the wrong results (as configure is done without the --host flag)?
The AOSP repo uses a pre-generated config.h, which is updated every time the upstream version is merged.

As a side note, it seems that the XMake repo for libbpf is unmaintained for quite some time (it uses libbpf version 0.3) 👎

[editso]

That's awesome! It seems like configure is only used to produce the config.h file, and then you compile the library yourself without make, did you have any issues with config.h producing the wrong results (as configure is done without the --host flag)? The AOSP repo uses a pre-generated config.h, which is updated every time the upstream version is merged.

As a side note, it seems that the XMake repo for libbpf is unmaintained for quite some time (it uses libbpf version 0.3) 👎

It seems that running ./configure directly does not have any impact. Yes, I removed the make-based compilation method and instead used the cc library for compilation. I have committed the code to a forked branch. Due to the significant changes I made, I am not sure if the pull request will be accepted

repo: https://github.com/editso/libbpf-sys-android/tree/android
ci: https://github.com/editso/libbpf-sys-android/actions/runs/9711879697