The problem as I understand it is not that writing to flash risks corruption; it’s that writing to flash — while simultaneously powering off — risks corruption to anywhere on the flash. So I can see no problem writing things very seldomly such as wpa_supplicant.conf as long as you don’t have a coinciding power cut. It’s not as though you write one file and it turns into a pumpkin.Heater wrote: ↑Mon Oct 09, 2017 11:10 amI think if you ever write anything to the SD card you are defeating the point of making this read-only root system. Even if you make a new partition to write data to. The SD card knows nothing about your partitions and file systems it only knows about blocks of data. If it's going to screw up, which they do, it might take down your read-only root as well.
I likely will do this for config files on my IoT device. Likely I will create a new partition (or a sub directory under/boot) and write those seldomly-changed files there, sync and flush buffers, symlink them to the real location, and take the slight risk that there won’t be a power cut during the moment they are written. Everything else will be read only or stored in the cloud.