SD Card Boot
SD card boot is a boot method in U-Boot for booting devices via an SD Card.
Genio 510/700-EVK and Genio 1200-EVK support SD card boot (via mmc device 1) in U-Boot since IoT Yocto v24.1. It also provides support for booting via the native mmc_boot script in U-Boot.
To use SD card boot, simply use a raw image downloader such as rufus or dd to flash the image onto the SD card. Therefore, users will need to build the wic raw image format for IoT Yocto.
Here, we provide a very simple example for SD card boot on U-Boot.
Build and Deploy IoT Yocto Image via SD Card Boot on Genio EVK
Developers can build the rity-demo-image and then boot the kernel and mount the file system via SD card on Genio EVK.
To reduce build/flash time and image size, users can also try the rity-bringup-image to test this feature.
The following sections describe the instructions to build and deploy IoT Yocto with raw image support and EFI (Extensible Firmware Interface) support for SD card boot.
Build IoT Yocto Supporting Raw Image
Edit your conf/local.conf to include the necessary settings for building a raw image with rity-bringup-image.
IMAGE_FSTYPES:append = " wic "
Build the rity-bringup-image:
MACHINE=genio-1200-evk bitbake rity-bringup-image
Deploy SD Card Boot with IoT Yocto Raw Image
Once the build is complete, locate the output files, which are typically found in the tmp/deploy/images/ directory within the corresponding MACHINE folder.
For example, if a user wants to boot Genio 1200-EVK via SD Card Boot.
Important
Please ensure that the EVK has a functional boot chain on the main storage, which can be either eMMC (embedded MultiMedia Card) or UFS (Universal Flash Storage), to support booting from an SD Card.
If the user is unsure whether the firmware supports SD card boot, please flash the new build rity-bringup-image on the EVK.
Then, deploy the raw disk image rity-bringup-image-genio-1200-evk.rootfs.wic to the SD card. We suggest using rufus on Windows OS and dd on Linux OS to flash the raw disk image to the SD card.
For Windows OS, you can use rufus to flash the raw disk image.
Rufus: Select The RAW Disk Image And Click “START” To Flash The SD card.
Rufus: The Process Of Flashing The RAW Disk Image Is Complete.
For Linux OS, unmount the SD card before using dd if the system detects and mounts it.
sudo umount /dev/sdX
sudo dd if=rity-bringup-image-genio-1200-evk.wic of=/dev/sdX bs=1M
sudo sync
sudo udisksctl power-off -b /dev/sdX
Remove the SD card from the PC after flashing it, then insert it into the SD card slot on the EVK.
Run the following command to reboot the system:
reboot
Hit any key when you see the message “Hit any key to stop autoboot”
Run the following commands in U-Boot mode:
setenv boot_targets mmc1
setenv storage mmc
setenv storage_dev 1
saveenv
reset
After reboot, the boot firmware on eMMC will load DTB, kernel, and rootfs from the SD card.
U-Boot 2022.10-gf7a807b03b (Dec 23 2024 - 11:06:43 +0000)
...
mmc1 is current device
Scanning mmc 1:8...
...
Scanning mmc 1:a...
Found U-Boot script /boot/fitImage
mmc1 is current device
...
MMC read: dev # 1, block # 421888, count 65536 ... 65536 blocks read: OK
## Loading kernel from FIT Image at 4a000000 ...
Build IoT Yocto Supporting Raw Image with EFI Boot Enabled
Users can also boot the SD card via the EFI boot process. Users need to build IoT Yocto with EFI support.
Edit your conf/local.conf to include the necessary settings for building a raw image with rity-bringup-image.
Remember to also add raw image support to this build.
MACHINE_FEATURES:append = " efi "
IMAGE_FSTYPES:append = " wic "
Build the rity-bringup-image:
MACHINE=genio-1200-evk bitbake rity-bringup-image
Deploy SD Card Boot with IoT Yocto with EFI Boot Enabled
Once the build is complete, locate the output files, which are typically found in the tmp/deploy/images/ directory within the corresponding MACHINE folder.
For example, if a user wants to boot Genio 1200-EVK via SD Card Boot.
Important
Please ensure the EVK has a functional boot chain on the main storage (eMMC or UFS) to support SD Card boot.
If the user is unsure whether the firmware supports SD card boot, please flash the new build rity-bringup-image on the EVK.
Then, deploy the raw disk image rity-bringup-image-genio-1200-evk.rootfs.wic to the SD card. We suggest using rufus on Windows OS and dd on Linux OS to flash the raw disk image to the SD card.
For Windows OS, you can use rufus to flash the raw disk image.
For Linux OS, unmount the SD card before using dd if the system detects and mounts it.
sudo umount /dev/sdX
sudo dd if=rity-bringup-image-genio-1200-evk.wic of=/dev/sdX bs=1M
sudo sync
sudo udisksctl power-off -b /dev/sdX
Remove the SD card from the PC after flashing it, then insert it into the SD card slot on the EVK.
Run the following command to reboot the system:
reboot
Hit any key when you see the message “Hit any key to stop autoboot”
Run the following commands in U-Boot mode:
setenv boot_targets mmc1
setenv storage mmc
setenv storage_num 1
saveenv
reset
After reboot, the boot firmware on eMMC will load DTB, kernel, and rootfs from the SD card.
When EFI boot is enabled, U-Boot will boot into GRUB. Press ‘ctrl-x’ or ‘enter’ to boot from GRUB menu.