How to use and build U-Boot on mx6sabresd
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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
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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 && 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 && sync
2. Booting from eMMC
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$ 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 && sync
$ sudo dd if=u-boot-dtb.img of=/dev/sdX bs=1K seek=69 && sync
Set SW6 to eMMC 8-bit boot: 11010110
3. Booting via Falcon mode
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$ 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 && 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 && 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.
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