How to use and build U-Boot on mx6sabresd: ---------------------------------- Currently there are four methods for booting mx6sabresd boards: 1. Booting from SD card via normal U-Boot (u-boot.imx) 2. Booting from eMMC via normal U-Boot 3. Booting via SPL (SPL and u-boot.img) 4. Booting via Falcon mode (SPL launches the kernel directly) 1. Booting from SD card via normal U-Boot ----------------------------------------- $ make mx6qsabresd_defconfig (If you want to build for mx6qsabresd) or $ make mx6dlsabresd_defconfig (If you want to build for mx6dlsabresd) $ make This will generate the image called u-boot.imx. - Flash the u-boot.imx binary into the SD card: $ sudo dd if=u-boot.imx of=/dev/sdb bs=1K seek=1 && sync 2. Booting from eMMC via normal U-Boot -------------------------------------- $ make mx6qsabresd_defconfig (If you want to build for mx6qsabresd) or $ make mx6dlsabresd_defconfig (If you want to build for mx6dlsabresd) $ make This will generate the image called u-boot.imx. - Flash the u-boot.imx binary into the eMMC: Set SW6 to download mode: 00001100 Plug a usb cable to USB-OTG and load the u-boot image using the imx_usb_loader tool (https://github.com/boundarydevices/imx_usb_loader): $ sudo ./imx_usb u-boot.imx In U-boot change the eMMC partition config: => mmc partconf 2 1 0 0 Mount the eMMC in the host PC: => ums 0 mmc 2 Flash the u-boot.imx binary $ sudo dd if=u-boot.imx of=/dev/sdX bs=1K seek=1 && sync Set SW6 to eMMC 8-bit boot: 11010110 3. Booting via SPL ------------------ Other method for building U-Boot on mx6qsabresd and mx6qpsabresd is through SPL. In order to do so: $ make mx6sabresd_spl_defconfig $ make This will generate the SPL image called SPL and the u-boot.img. - Flash the SPL image into the SD card: $ sudo dd if=SPL of=/dev/sdb bs=1K seek=1 && sync - Flash the u-boot.img image into the SD card: $ sudo dd if=u-boot.img of=/dev/sdbbs=1K seek=69 && sync 4. Booting via Falcon mode -------------------------- $ make mx6sabresd_spl_defconfig $ make This will generate the SPL image called SPL and the u-boot.img. - Flash the SPL image into the SD card: $ sudo dd if=SPL of=/dev/sdb bs=1K seek=1 oflag=sync status=none && sync - Flash the u-boot.img image into the SD card: $ sudo dd if=u-boot.img of=/dev/sdbbs=1K seek=69 oflag=sync status=none && sync Create a partition for root file system and extract it there: $ sudo tar xvf rootfs.tar.gz -C /media/root The SD card must have enough space for raw "args" and "kernel". To configure Falcon mode for the first time, on U-Boot do the following commands: - Setup the IP server: # setenv serverip - Download dtb file: # dhcp ${fdt_addr} imx6q-sabresd.dtb - Download kernel image: # dhcp ${loadaddr} uImage - Write kernel at 2MB offset: # mmc write ${loadaddr} 0x1000 0x4000 - Setup kernel bootargs: # setenv bootargs "console=ttymxc0,115200 root=/dev/mmcblk1p1 rootfstype=ext4 rootwait quiet rw" - Prepare args: # spl export fdt ${loadaddr} - ${fdt_addr} - Write args 1MB data (0x800 sectors) to 1MB offset (0x800 sectors) # mmc write 18000000 0x800 0x800 - Press KEY_VOL_UP key, power up the board and then SPL binary will launch the kernel directly.