just to follow up with this: I have built a library (.a) using both the ESP IDF and with the Arduino ULP port but both are unable to find the ulp_entry variable:
(.literal._Z17start_ulp_programv+0x0): undefined reference to ‘ulp_entry’.
So other ulp_ variables are being recognized just not that one variable- the entry point into the assembler code.
I see ulp_entry (and ulp_exit) in the .ld file:
PROVIDE (ulp_entry = 0x50000190 );
so I think it is linked into the object file and in the .a library.
I added the library to my mos.yml using:
both local and remote build have the same error.