Micropython rp2 fails to build on windows systems.
When attempting to build micropython for rp2040 in a windows environment, the make/cmake environment generates a command line that exceeds the windows10/cmd.exe line length limit of 8191 characters.
This is because the RP2 SDK requires about 3k worth of C include paths, and the list of files compiled that is generated on a single command line is about 6k (depending on exact path names.)
Extensive discussion and whining here: https://www.raspberrypi.org/forums/viewtopic.php?f=144&t=306333
I'll add that compiling all the C files for micropython with a single command line seems ... dangerously likely not to scale well on other build platforms as well.
Build broken?
I'm unable to build on a Ubuntu 18.04 system. Following the instructions in the SDK docs (and some alternatives from forums), I still end up here:
/net/src/platforms/raspberry_pi/rp2040/micropython/ports/rp2$ make [ -d build-PICO ] || cmake -S . -B build-PICO -DPICO_BUILD_DOCS=0 -DMICROPY_BOARD=PICO CMake Error: The source directory "/net/src/platforms/raspberry_pi/rp2040/micropython/ports/rp2/build-PICO" does not exist.
If I create the missing directory it dies with an error about missing target.