We are planning to use iMX8 for an Automotive project with Ethernet connectivity an very short startup time requirements.
So we want to use the Cortex-M4 core for RTOS/AutoSAR which can handle initial requests on Ethernet very quickly. The larger Cortex-A cores shall run Linux and have more relaxed startup times but also need to access Ethernet - actually with quite a large data rate which the M4 can not handle.
So how can the M4 and the A-cores share the Ethernet without interference ?
Both cores can have different IP addresses if required.
You can not use the same Ethernet interface with different OSes.
You need to drive Ethernet from one OS and access it from another using something like messaging unit.
However it is not a good idea. This way you loose speed and realtime.
If you mean i.MX8 processor not i.MX8M please note that it has 2 Ethernet interfaces.
So yo can use one with RTOS runing on M4 core and another with Linux runing on A ones.