Any way to disable SPI reads from flash?

Hi, I’ve been trying to find a way to take advantage of more of the GPIO pins and have run into problems disabling the SPI flash. I am running from a SD card using extroot but I can’t find a way to make the kernel understand that it needs to access the SD card, not the SPI flash. As soon as I unmap the GPIOs used for SPI (By echoing the device to unmap to the unmap “file” in /sys) I start seeing errors about failures to read from the SPI flash device, which generally causes a kernel panic. I’ve tried unmounting the squashfs device beforehand or mounting the SD card over that device (The SD card has a full copy of the system), but it never seems to work. I’m guessing this is due to the way the read-only flash filesystem is overlaid onto the active FS on the SD card but I haven’t found a way to remove or replace that mapping once the overlay is set up.

Any ideas?