NativeAOT library fails to load on linux-bionic-arm64 due to missing symbol

[TrevTV]

Description

Newer versions of the .NET SDK require the symbol __aarch64_cas16_acq_rel on linux-bionic-arm64 NativeAOT builds, however that doesn't exist so the libraries are unable to be loaded.

Reproduction Steps

A reproduction project is available in this repo. The library (in the NAOTLib folder) can be compiled using these commands, with the environment variable ANDROID_NDK_ROOT set to a folder path containing NDK r21e.

dotnet restore
dotnet publish -r linux-bionic-arm64 -p:DisableUnsupportedError=true -p:PublishAotUsingRuntimePack=true

The loader side (in the LoaderApp folder) is compiled with gradlew installDebug though any other loading method should have the same result.
global.json can be changed to see the different results per version.
https://github.com/TrevTV/LinuxBionicSymbolExample

Expected behavior

The library loads without error.

Actual behavior

This error occurs.

java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "__aarch64_cas16_acq_rel" referenced by "/data/app/~~Y6IeYBqGjhnjqVvMUKAG_g==/app.trev.naotloader-X9_xowBAe5-seTAfiyJzXQ==/lib/arm64/libnaotlib.so"...

Regression?

I was able to narrow down the failure to .NET 9.0.103 and versions after.
.NET 9.0.102 and .NET 9.0.200-preview.0.25057.12 are both versions I know work correctly.

Known Workarounds

Use .NET 9.0.102 or older when compiling.

Configuration

The library is compiled on Windows 11 24H2 (64-bit), but is cross-compiled for arm64-v8a using Android NDK r21e.
It was tested on my Pixel 9 Pro running Android 15.
I have not tested other architectures.

Other information

No response

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[MichalStrehovsky]

I think we bumped the Android NDK used to build the runtime in 9.0.103 of SDK (should correspond to https://github.com/dotnet/runtime/releases/tag/v9.0.2 of dotnet/runtime).

dotnet/dotnet-buildtools-prereqs-docker#1278

Your Android NDK r21e is likely too old. Can you try with a newer NDK (ideally 27)?

[TrevTV]

Ah yep confirmed that fixed it, I was locked onto r21e due to a non-.NET dependency so it looks like I'll have to figure out that problem then. Thank you!

[MichalStrehovsky]

Cc @vitek-karas - not sure what the delivery mechanism of the Android NDK is for supported configurations (native AOT is experimental and not fully supported), but looks like we have a requirement to be somewhat close to what dotnet/runtime was built with; bumps in servicing could be breaking (doesn't matter too much for native AOT right now since it's experimental).

[vitek-karas]

We had to upgrade even in servicing branches due to compliance. Going forward we plan to upgrade the NDK around RC timeframe and hopefully will not have to upgrade the servicing branches at all. More details here: https://github.com/dotnet/runtime/blob/main/docs/workflow/testing/libraries/testing-android.md#upgrading-the-android-ndk-version-in-ci-pipelines