Boot from additional flash module

[gmussi]

Dear users in this community,

I am currently working on an ESP32 firmware, with a size of 3.5MB.
I need to implement OTA procedure in this project.

Since the ESP32 board only has 4MB flash, I am trying to achieve the following:

1) Use a W25QXX 4MB additional flash module
2) Alternate between this flash module and the ESP32 flash module for booting
3) When botting from the ESP32 flash module, OTA procedure with upload firmware to external flash module, and vice-versa.

I have the hardware wired, but I haven't found yet an example of how to achieve this.
I would be very helpful for any directions you could give me.

Thanks for your time!