[yocto] ARM CPU version question

[Steve Pavao]

What’s the recommended way to be able to propogate target-specific compile-time CPU tune information to affect the build of a source file in my own custom layer?

For example, if I’m building for an arm6-based target, I’d like to be able to have the __ARM_ARCH_6__ symbol be available when the Yocto system builds my custom layer.  The BSP for such a target obviously defines this symbol when building its files for such a target.  Is there an easy way to propagate this information to my own custom layer, to affect my own sources?  Maybe my recipe needs to include certain conf files from other layers such as meta or the BSP layer?

Currently, I notice that architecture-level symbols are available to my custom layer at compile time, such as __aarch64_ and __arm__, but not CPU tune information, such as __ARM_ARCH_6__.

- Steve Pavao
Korg R&D