SD interface through EMIO for PYNQ image

Hello everyone,

I have a custom board with Zynq-7020 device on it. It has 512MB DDR3, 32MB FLASH memory on board but SD card interface is not routed. I have several FPGA pins available to implement 1bit SD interface through EMIO. My idea is to run FSBL → u-boot → kernel from FLASH memory and load PYNQ rootfs from SD card through EMIO SD interface.
I know that PYNQ does not load bitstream on bootup (I already know solution for this). My question is if it is possible to run PYNQ image like this and what will happen when loading PYNQ overlay (if overlay will also have EMIO SD interface)? Will this work? What special care must be taken?


Welcome =]

I am afraid from the basic structure of PYNQ this is highly restricted.
This can be applied to only and only a non-reconfigurable PYNQ environment case.
This is means FPGA manager is not able to reconfigure as the PL-PS of the major system is required to be untouched.
If a overlay is reloaded the PL will be lost and result in a system crash of major memory is stop working.

However, if you only intended to use Python on FPGA environment with fixed design this can work perfectly with no issue.