Hi Gordon,
there's no such example but you can take a look at this thread:
https://community.nxp.com/t5/MPC5xxx/MPC5748G-dual-core-projects-only-work-when-using-the-first-and/...
You can see there how to create shared segment in the linker files. Just make sure that the segment is initialized due to ECC by startup files. Startup files use symbols from linker file to know the start address and size of RAM. Each core then initializes own RAM area. You can change the symbols in linker file for boot core to initialize also this shared segment.
Next point - I recommend to configure shared RAM as cache inhibited. This can be done by SMPU. You can find SW example for SMPU here:
c:\NXP\S32DS_Power_v2.1\S32DS\software\S32_SDK_S32R294_RTM_1.0.0\examples\S32R294\driver_examples\system\smpu_protection\
And if it is necessary to ensure data coherency, you can use semaphores:
c:\NXP\S32DS_Power_v2.1\S32DS\software\S32_SDK_S32R294_RTM_1.0.0\examples\S32R294\driver_examples\system\sema42_multicore\
Regards,
Lukas