Issue with libatomic in recent ARC GCC versions

Hello Alexey,

I hope this message finds you well.

We are seeing a number of build failures due to libatomic on ARC 750d. Indeed, it seems like libatomic.so needs __atomic_test_and_set (the symbol is undefined in the library), but nothing provides it.

Example 1 with libcap:

http://autobuild.buildroot.net/results/297/2975043dd2c9d537e7a5b5634e7ad047a7a08afc/build-end.log

Example 2 with android-tools:

http://autobuild.buildroot.net/results/c02/c02ab71087eb70fc6bd5d40ecc509cfe0df36233/build-end.log

And indeed, looking at libatomic.so:

15: 00000000 0 NOTYPE GLOBAL DEFAULT UND __atomic_test_and_set

This issue happens with both GCC arc-2024.12-release and the upstream GCC 15.x.

Aside from this specific issue, we're seeing less and less contributions from Synopsys to the ARC support (not to say zero contributions). I was the one doing recently an update of ARC toolchain components. But there are ARC related build failures, we get essentially no feedback, even though a daily e-mail is sent with build failure reports.

Should we drop support for the ARC CPU architecture in Buildroot? Without more active support from Synopsys, it's likely what will happen.

Thanks a lot for your feedback!

Thomas

Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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