Hello Marcello Bellini,
There is not a real time OS BSP for the Cortex A7 on the i.MX7. Most users use the Cortex M4 for real time operations and run Linux on the Cortex A7 so this is the supported configuration.
You may port a real time OS on the Cortex A7 yourself but it’s not a trivial task. There is also NXP Professional Services who may be of help.
My apologies for the inconvenience.
Regards,