[Answered]: MMU and un-mapped flash entry numbers
Posted: Sat Feb 24, 2018 11:52 pm
Using the language in the ESP32 technical reference relating to MMU ... for flash we have 256 entries where each entry corresponds to a 64K range of address space. We can map an entry to a corresponding 64K of flash storage. Each entry in the MMU table consists of:
8 bits of flash storage page identity
1 bit of MMU table entry defined/undefined 0 = defined, 1 = undefined.
With this background, here comes my question.
If I access an address in storage in the ESP32 that is governed by the MMU flash mapping and the corresponding entry for that region of memory is flagged as undefined (control bit is 1), what ... if anything ... does that mean? Will an exception be thrown? Is there some form of "implicit" mapping?
8 bits of flash storage page identity
1 bit of MMU table entry defined/undefined 0 = defined, 1 = undefined.
With this background, here comes my question.
If I access an address in storage in the ESP32 that is governed by the MMU flash mapping and the corresponding entry for that region of memory is flagged as undefined (control bit is 1), what ... if anything ... does that mean? Will an exception be thrown? Is there some form of "implicit" mapping?