Raspberry Pi Pico 2 Buildroot

How to build:

git clone https://github.com/Mr-Bossman/pi-pico2-linux

cd pi-pico2-linux

git submodule update --init

# cd buildroot
# make BR2_EXTERNAL=$PWD/../ raspberrypi-pico2_defconfig
make -C buildroot BR2_EXTERNAL=$PWD/ raspberrypi-pico2_defconfig

make -C buildroot

make -C psram-bootloader flash-kernel

Designed to work with SparkFun Pro Micro - RP2350

NOTES on SDK

This project uses the sdk and tools installed to ~/.pico-sdk/. To use the tools and sdk installed to another location see this issue or the following.

export PICO_SDK_PATH=~/example_sdk/sdk/2.0.0/
export PICO_TOOLCHAIN_PATH=~/example_sdk/toolchain/13_2_Rel1
export pioasm_DIR=~/example_sdk/tools/2.0.0/pioasm
export picotool_DIR=~/example_sdk/picotool/2.0.0/picotool

make flash-kernel

NOTES on Atomics

On page 307 of the RP2350 Datasheet MCAUSE register CODE 7 says:

Store/AMO access fault. A store/AMO failed a PMP check, or encountered a downstream bus error. Also set if an AMO is attempted on a region that does not support atomics (on RP2350, anything but SRAM).

Atomics will only work in SRAM, the kernel is located PSRAM, not SRAM. The lr and sr atomic load and store will always return error in this region causing most code using them to behave incorrectly. Most implementations assume lr and sr will eventually succeed.

Use on other boards

This only works on the RP2350 RISC-V cores.

If you want to run this on other boards, please change the PICO_BOARD variable in CMakeLists.txt. set(PICO_BOARD sparkfun_promicro_rp2350 CACHE STRING "Board type")

You will also need to set the psram CS pin with the SFE_RP2350_XIP_CSI_PIN macro in bootloader.c. As of now the only psram chip tested is the APS6404L and any others may not work.