mx6sabresd

How to use and build U-Boot on mx6sabresd

The following methods can be used for booting mx6sabresd boards:

  1. Booting from SD card

  2. Booting from eMMC

  3. Booting via Falcon mode (SPL launches the kernel directly)

1. Booting from SD card via SPL

mx6sabresd_defconfig target supports mx6q/mx6dl/mx6qp sabresd variants.

In order to build it:

$ make mx6sabresd_defconfig
$ make

This will generate the SPL and u-boot-dtb.img binaries.

  • Flash the SPL binary into the SD card:

$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 conv=notrunc && sync
  • Flash the u-boot-dtb.img binary into the SD card:

$ sudo dd if=u-boot-dtb.img of=/dev/sdX bs=1K seek=69 conv=notrunc && sync

2. Booting from eMMC

$ make mx6sabresd_defconfig
$ make

This will generate the SPL and u-boot-dtb.img binaries.

  • Boot first from SD card as shown in the previous section

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 SPL and u-boot-dtb.img binaries into the eMMC:

$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 conv=notrunc && sync
$ sudo dd if=u-boot-dtb.img of=/dev/sdX bs=1K seek=69 conv=notrunc && sync

Set SW6 to eMMC 8-bit boot: 11010110

3. Booting via Falcon mode

$ make mx6sabresd_defconfig
$ make

This will generate the SPL image called SPL and the u-boot-dtb.img.

  • Flash the SPL image into the SD card

$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 oflag=sync status=none conv=notrunc && sync
  • Flash the u-boot-dtb.img image into the SD card

$ sudo dd if=u-boot-dtb.img of=/dev/sdX bs=1K seek=69 oflag=sync status=none conv=notrunc && 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 <server_ip_address>
    
  • 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.