multi-core NIOS boot

Hi Daixiwen,

thanks for your answer.

The two NIOS shall run *different* softwares.

From my understanding the boot process that you are suggesting is the following one

[1] - FPGA configures itself by reading *.sof from EPCS. From now on both NIOS start working.

[2] - NIOS_A keeps NIOS_B to reset state and executes boot-copier located in EPCS controller boot-rom

[3] - Once NIOS_A boot has completed, NIOS_A application is launched and it releases NIOS_B from reset

[4] - NIOS_B executes the bootloader located into on-chip memory boot-rom

[5] - Once NIOS_B bootloader has finished the system is up and running =)

I guess that keeping NIOS_B in reset state while at step [2] can be achieved by modifying the default boot-loader of NIOS_A.

I've got a doubt about this point: soon after step [1] completes both NIOS start to execute rommed bootloaders that in turn both try to access EPCS device.

At this point NIOS_A bootloader should be able to keep NIOS_B in reset and, in doing so, it grants exclusive access to EPCS device.

This works fine if NIOS_A start a bit before NIOS_B. But, from my understanding, there is no guarantee that the latter condition is met.

Theoretically both NIOS start soon after step [1] completes and both try to access EPCS device potentially compromising both NIOS boot process.

Is this condition possibile? NIOS_B should be kept in reset in another way?

Last question : someone know how is possible to place a custom bootloader to boot-rom?

Thanks again