Hi Francois,
I’m sorry that it don’t help you.
I made test for Kinetis MCU in the same CW IDE and it is supported. My understanding is this attribute is not supported by S12 Compiler. The ARM Kinetis use the GCC which supports this option. In case I take such suggestion how to solve it I will send you message.
Sorry I can’t help you more.
Best Regards,
Stano.