How to use and build U-Boot on mx6sabresd
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The following methods can be used for booting mx6sabresd boards:
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1. Booting from SD card
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2. Booting from eMMC
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3. Booting via Falcon mode (SPL launches the kernel directly)
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1. Booting from SD card via SPL
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-------------------------------
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mx6sabresd_defconfig target supports mx6q/mx6dl/mx6qp sabresd variants.
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In order to build it:
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$ make mx6sabresd_defconfig
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$ make
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This will generate the SPL and u-boot.img binaries.
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- Flash the SPL binary into the SD card:
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$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 && sync
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- Flash the u-boot.img binary into the SD card:
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$ sudo dd if=u-boot.img of=/dev/sdX bs=1K seek=69 && sync
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2. Booting from eMMC
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--------------------
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$ make mx6sabresd_defconfig
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$ make
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This will generate the SPL and u-boot.img binaries.
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- Boot first from SD card as shown in the previous section
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In U-boot change the eMMC partition config:
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=> mmc partconf 2 1 0 0
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Mount the eMMC in the host PC:
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=> ums 0 mmc 2
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- Flash SPL and u-boot.img binaries into the eMMC:
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$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 && sync
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$ sudo dd if=u-boot.img of=/dev/sdX bs=1K seek=69 && sync
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Set SW6 to eMMC 8-bit boot: 11010110
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3. Booting via Falcon mode
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--------------------------
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$ make mx6sabresd_defconfig
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$ make
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This will generate the SPL image called SPL and the u-boot.img.
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- Flash the SPL image into the SD card:
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$ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 oflag=sync status=none && sync
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- Flash the u-boot.img image into the SD card:
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$ sudo dd if=u-boot.img of=/dev/sdX bs=1K seek=69 oflag=sync status=none && sync
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Create a partition for root file system and extract it there:
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$ sudo tar xvf rootfs.tar.gz -C /media/root
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The SD card must have enough space for raw "args" and "kernel".
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To configure Falcon mode for the first time, on U-Boot do the following commands:
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- Setup the IP server:
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# setenv serverip <server_ip_address>
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- Download dtb file:
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# dhcp ${fdt_addr} imx6q-sabresd.dtb
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- Download kernel image:
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# dhcp ${loadaddr} uImage
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- Write kernel at 2MB offset:
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# mmc write ${loadaddr} 0x1000 0x4000
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- Setup kernel bootargs:
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# setenv bootargs "console=ttymxc0,115200 root=/dev/mmcblk1p1 rootfstype=ext4 rootwait quiet rw"
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- Prepare args:
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# spl export fdt ${loadaddr} - ${fdt_addr}
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- Write args 1MB data (0x800 sectors) to 1MB offset (0x800 sectors)
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# mmc write 18000000 0x800 0x800
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- Press KEY_VOL_UP key, power up the board and then SPL binary will
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launch the kernel directly.
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