Cortex-A12 GNU example build

This example demonstrates that ThreadX builds and links for the Cortex-A12. It is not a runnable image.

tx_initialize_low_level.S here is the generic ARMv7-A skeleton: it provides the interrupt handler shell but programs no interrupt controller and no timer, and it does not install a vector table. ThreadX will therefore not receive a timer tick on this example, so threads that rely on time slicing or on tx_thread_sleep() will not run as intended.

For a model targeted example with a GIC, a private timer and a vector table installed, see the Cortex-A5, A7, A8 or A9 example builds. Those carry the matching support files (MP_GIC, MP_PrivateTimer, v7.s) and target the Versatile Express fixed virtual platforms.

Building

./build_threadx.sh          # the ThreadX library, tx.a
./build_threadx_sample.sh   # the sample image

Set TOOLCHAIN=atfe to build with Arm Toolchain for Embedded instead of the GNU toolchain:

TOOLCHAIN=atfe ATFE_CLANG=/path/to/clang ./build_threadx.sh
TOOLCHAIN=atfe ATFE_CLANG=/path/to/clang ./build_threadx_sample.sh