Why isn't there an assembler for the ESP32 version of uLisp?

#1

@dragoncoder047 wrote:

The ESP32 processors are designed with a “write XOR execute” design that makes on-the-fly machine code generation impossible

More precisely, it’s a decision taken in the design of the IDF (ESP32 IoT Development Framework):

This is caused by the memory protection of ESP-IDF: it assumes all executable code comes from the project binary, and that an attempt to re-write code or to execute data is someone maliciously trying to break into the system, and as such needs to be stopped.

It looks like the only way around it would be to recompile the ESP-IDF libraries; at this point I thought it wasn’t worth pursuing it.

See my full discussion on the ESP32 forum here:

How can I write machine code into RAM and then execute it?

Newbie, comparison to MicroPython
#2

Excellent.

I think I will get the Pico and give it a shot since I need one anyways.

Thanks!

#3

So were you able to find the assembler that ESP32’s use? I thought this wasn’t documented.

It sounds like you could set the partitions.csv file to utilize the maximum amount of flash space for app0, and then read and write from there. There may be some extra incantations necessary to turn off encrypted or readonly flags for that partition to allow writing and executing code.

https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/partition-tables.html

#4

So were you able to find the assembler that ESP32’s use? I thought this wasn’t documented.

For the original ESP32 I think this is the document:

Xtensa Instruction Set Architecture (ISA) Reference Manual

#5

Note that the ESP32-C3, ESP32-C5, and ESP32-C6 boards are based on a RISC-V processor, and if the ESP-IDF didn’t prevent execution of code in RAM the existing uLisp RISC-V assembler would be usable with these.