When to use AT_HWCAP or AT_HWCAP2

[Jeffrey Walton]

Hi Everyone,

Please forgive my ignorance. The getauxval (3) man page discusses both
AT_HWCAP and AT_HWCAP2. I'm less clear on about when I should use one
or the other?

For example, suppose I'm on an Aarch64 Opteron. Testing shows I need
AT_HWCAP for HWCAP_AES, HWCAP_PMULL, etc. Now suppose I am in a
Aarch32 execution environment on the same machine. Do I check AT_HWCAP
or AT_HWCAP2? How do I know the difference at runtime?

Thanks in advance.

Jeff