Booting linux on ESP32

Sources:

https://github.com/jcmvbkbc/esp-idf.git linux

https://github.com/jcmvbkbc/linux-xtensa.git xtensa-5.18-esp32

buildroot mainline

$ cd examples/get-started/linux_boot
$ idf.py build
$ idf.py -p /dev/ttyUSB0 flash
$ parttool.py -p /dev/ttyUSB0 write_partition --partition-name linux --input xip-esp32-esp32/arch/xtensa/boot/xipImage
$ parttool.py -p /dev/ttyUSB0 write_partition --partition-name rootfs --input build-xtensa-nommu-de108/images/rootfs.cramfs