This directory provides a bootloader image that loads a Linux initramfs that exports common block devices (EMMC, NVMe) as USB mass storage devices using the Linux gadget-fs drivers.
This allows Raspberry Pi Imager to be run on the host computer and write OS images to the Compute Module block devices.
WARNING: This image used a 32-bit kernel and is NOT compatible with Pi5.
To run load the USB MSD device drivers via RPIBOOT run
cd mass-storage-gadget
../rpiboot -d .
N.B. This takes a few seconds longer to initialise than the previous mass storage implementation. However, the write speed should be much faster now that all of the file-system code is running on the ARM processors.
The mass-storage-gadget image automatically enables a UART console for debugging (user root empty password).
If secure-boot is enabled then boot.img must be signed with the customer private key file.
KEY_FILE=$HOME/private.pem
rpi-eeprom-digest -i boot.img -o boot.sig -k "${KEY_FILE}"The buildroot configuration and supporting patches is available on the mass-storage-gadget branch of the Raspberry Pi buildroot repo.
git clone --branch mass-storage-gadget git@github.com:raspberrypi/buildroot.git
cd buildroot
make raspberrypicm4io_initrd_defconfig
makeThe output is written to output/target/images/sdcard.img and can be copied
to boot.img