out-of-tree build

[yf13]

I am totally new to micropython.

It seems that out-of-tree building is available at least for mpy-cross as I can do below on Ubuntu 22.04 host with gcc 11.4:

$ BUILD=$PWD make -C ~/Projects/micropython/mpy-cross

But when I tried same method for ports/unix, I got errors:

$ BUILD=$PWD make -C ~/Projects/micropython/port/unix
...
CC ../../py/frozenmod.c
make -C "/home/yf/Projects/micropython/mpy-cross" USER_C_MODULES=
make[1]: Entering directory '/home/yf/Projects/micropython/mpy-cross'
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
CC ../py/mpstate.c
...
CC ../py/gc.c
CC ../py/pystack.c
CC ../py/qstr.c
/tmp/bbb/genhdr/qstrdefs.generated.h:4:17: error: unsigned conversion from ‘int’ to ‘unsigned char’ changes value from ‘5381’ to ‘5’ [-Werror=overflow]
    4 | QDEF0(MP_QSTR_, 5381, 0, "")

Meanwhile In place build of ports/unix works smoothly.
So I am wondering how the situation of out-of-tree build is? Is it a design goal?

[yf13]

It seems that out-of-tree building can be done like below, if $(TOP)/mpy-cross/build/mpy-cross exists:

$ cd ~/Projects/micropython
$ ls -l mpy-cross/build/
-rwxrwxr-x 1 yf yf 436440 Jun  7 22:59 mpy-cross
$ BUILD=/tmp/bbb make -C ports/unix

This doesn't feel right as it assumes an in-tree mpy-cross artifact. If there are ways for out-of-tree build, please teach.

[Josverl]

Can you explain the setup or structure that you want or need.

"out-of-tree build" leaves a lot to the imagination.

Also, each port contains a readme.md with detailed build instructions

[yf13]

@Josverl I simply meant to have aritacts generated out of the source tree, or keep source folder unchanged when building a port.

I found with minor tweaks both unix and qemu ports can do it like below:

$ cd ~/Projects/micropython
$ make -C ports/qemu/ BUILD=/tmp/aaa MICROPY_MPYCROSS=~/bin/mpy-cross BOARD=VIRT_RV32 test -j
$ make -C ports/unix/ BUILD=/tmp/bbb MICROPY_MPYCROSS=~/bin/mpy-cross test -j

Meanwhile, the in-place build still works:

$ cd ~/Projects/micropython
$ make -C ports/qemu BOARD=VIRT_RV32 test -j
$ make -C ports/unix test -j

So it seems that we are not far from out-of-tree build?