So...

1. It only affects 64mbit psram parts
2. Even though the lyontek and espressif 64mbit psram are spec'ed to 85c they have presented issues above 65c

?

Is this true for both 1.8v and 3.3v parts? At 40mhz?

Well in 3/4 encoding there are only 192 bits per block and with blk3 part reserve 48 are reserved so you should be able to use the other 144 bits (which are also non contiguous) but you have to program them pre-encoded which I don't think espefuse supports.

Yes you would probably need to add some markers to the linker script to figure out where the stub ends.

https://github.com/espressif/esp-idf/blob/66fd7e9cc3d5327d94b5bf681100d1e3f2cf73e1/components/esp32/include/esp_err.h#L100-L104 https://github.com/espressif/esp-idf/blob/ae5df5d6ce7c9abd9c8c4731ced96031c29f7fc1/make/project.mk#L327-L329 If you have assertions disabled it should not embed these refer...

No it is not required but it can improve accuracy of timekeeping