Hi Karlphy,
There is an example in MCSDK under tools/boot_loader/examples/srio/srioboot_helloworld that demonstrates multicore boot. Essentially once your primary boot core wakes up it needs to write the Boot MAGIC address for the core in the address locations corresponding to the secondary core and issue a IPC interrupt to notify the secondary cores to start executing code from memory location specified by their boot magic address.
Please refer to the main function in that example and let us know if you have any further questions regarding this issue.
Regards,
Rahul