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You can get a toolchain from apt or from Arm directly: https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
Make sure you choose the correct host and target triples. If you want to target Linux (which you do 99% of the time) choose one with -linux in the name.
I recommend getting Arm’s because it’ll have the latest feature support. You could also use clang but you’ll need a sysroot, which you get from the same place anyway.
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