cpu/esp32: fix documentation about toolchain installation

[benpicco]

Contribution description

It looks like the submodule folders in esp-idf got renamed, this breaks the instructions in the documentation as it instructs the user to get them all to the latest state immediately (git clone --recursive):

$ git clone --recursive https://github.com/espressif/esp-idf.git # checks out all the submodules to the current state/name
$ cd esp-idf
$ git checkout -q f198339ec09e90666150672884535802304d23ec # uh oh
warning: unable to rmdir 'components/asio/asio': Directory not empty
warning: unable to rmdir 'components/bootloader/subproject/components/micro-ecc/micro-ecc': Directory not empty
warning: unable to rmdir 'components/bt/controller/lib': Directory not empty
warning: unable to rmdir 'components/bt/host/nimble/nimble': Directory not empty
warning: unable to rmdir 'components/cbor/tinycbor': Directory not empty
warning: unable to rmdir 'components/esp_wifi/lib_esp32': Directory not empty
warning: unable to rmdir 'components/expat/expat': Directory not empty
warning: unable to rmdir 'components/lwip/lwip': Directory not empty
warning: unable to rmdir 'components/mqtt/esp-mqtt': Directory not empty
warning: unable to rmdir 'components/protobuf-c/protobuf-c': Directory not empty
warning: unable to rmdir 'components/unity/unity': Directory not empty
warning: unable to rmdir 'examples/build_system/cmake/import_lib/main/lib/tinyxml2': Directory not empty
$ cd components/esp32/lib
$ git checkout -q 534a9b14101af90231d40a4f94924d67bc848d5f

fatal: reference is not a tree: 534a9b14101af90231d40a4f94924d67bc848d5f

Now when trying to build e.g. examples/gnrc_networking, this results in errors that the libraries can not be found for linking, the build fails.

If instead we checkout the submodules after bringing the main repo to a known state, things work again

Testing procedure

Follow the instructions for installing the toolchain:

mkdir -p $HOME/esp
cd $HOME/esp
git clone https://github.com/gschorcht/xtensa-esp32-elf.git

git clone https://github.com/espressif/esp-idf.git
cd esp-idf
git checkout f198339ec09e90666150672884535802304d23ec
git submodule init
git submodule update
# the submodule are now already in a known good state, no extra checkout needed

In RIOT, do

export PATH=$HOME/esp/xtensa-esp32-elf/bin:$PATH
export ESP32_SDK_DIR=$HOME/esp/esp-idf

sed -i '1iUSEMODULE += esp_wifi' examples/gnrc_networking/Makefile
make -j BOARD=esp32-wroom-32 -C examples/gnrc_networking

Issues/PRs references

discovered when testing #11997

[gschorcht]

Seems to work. Wouldn't it be better to checkout with -q option? The whole warning/information text might be misleading for the use.

[benpicco]

Different tastes I guess. At first I was wondering if -q was doing anything special since I usually don't use it.

But I also think it's good to see what's going on, no warnings afair.

[gschorcht]

Different tastes I guess.

Indeed. You know the UNIX principle. No messages are good messages.

But I also think it's good to see what's going on, no warnings afair.

OK

[gschorcht]

@benpicco Many thanks for figuring it out. I didn't realize it. When I was writing the documentation it worked in documented way.