I have phyBOARD-MIRA i.MX6 development board from PHYTEC. It comes with preinstalled barebox bootloader on NAND Flash, and one can build embedded Linux distribution (more or less) easily using Yocto and documentation of PHYTEC.
I have built new embedded Linux distribution using Yocto (with new barebox), I have copied it to SD Card as shown later below, set switch S2 on phyBOARD-MIRA i.MX6 to ON so that Linux boots from SD Card, and I was happy with how it works. Barebox bootloader is still old Barebox from NAND Flash.
Now I am trying to flash everything from this SD Card to NAND Flash on embedded board. When I stop autoboot of embedded board and try flashing barebox like this:
barebox_update -t nand /dev/mmc0.barebox
I get following error:
UPDATE: Image is not of type ARM barebox image but of type MBR sector
update failed
This is what is written in documentation of PHYTEC:
In case that your phyBOARD-Mira i.MX 6 does not start anymore due to a damaged bootloader, you need to boot from an SD card. This SD card must be formatted in a special way, because the i.MX 6 does not use file systems. Instead it is hard coded at which sectors of the SD card the i.MX 6 expects the bootloader.
Bitbake, a tool integrated in Yocto, builds an image with the ending *.sdcard which fulfills the requirements mentioned above. So we can copy this image to an SD card with the help of dd.
Now use the following command to create your bootable SD card:
sudo dd if=phytec‐qt5demo‐image‐phyboard‐mira‐imx6‐*.sdcard
of=/dev/<DEVICE>
I am using dd to create bootable sd card, I am only using Cygwin dd instead on normal dd from Linux. They are probably same, but SD card seems to still have old NTFS or exFAT filesystem which is bad for my barebox. I have three components of embedded Linux distribution which stem from this *.sdcard file: barebox, linuximage and oftree, but MBR sector at the beginning of SD card seems to make SD card less usable.
Did anyone have similar problems, and is there anything more useful than this dd command?
Now I am trying to flash everything from this SD Card to NAND Flash on embedded board.
It's usual for SD-Cards to have an on-disk partition table, e.g. MBR in your case, but this is not the norm for NAND. Even if you flash your SD-Card completely to NAND, it will not behave as you expect. The Phytec BSP can probably generate images for NAND as well, which you should rather use.
A usual setup is having the NAND partitioning described in the device tree, then you use barebox_update to install barebox into the NAND and then the kernel, device tree and rootfs are in an UBI/UBIFS.
I think the Phytec documentation should help you with all that. In general, it's often easiest to flash over USB:
barebox$ usbgadget -A /dev/nand0.root(root-nand)u -b
host$ fastboot getvar all # list all flashable partitions
host$ fastboot flash root-nand my-image.ubi
host$ fastboot flash bbu-nand barebox-phytec-something.img
Replace /dev/nand0.root with whatever the name of your root partition is.
When I stop autoboot of embedded board and try flashing barebox like this:
barebox_update -t nand /dev/mmc0.barebox UPDATE: Image is not of type ARM barebox image but of type MBR sector update failed
That's expected: If you run devinfo, you'll see that the barebox partition starts at address 0. That's ok, because the i.MX6 BootROM only cares about what's at location 0x400 of the SD-Card. barebox_update though will try to guess what kind of image it's given to protect your from soft-bricking your device.
As you are pointing it at the start of the SD-Card, it will see the MBR 0xaa55 magic and tell you that it's not what it expects.
In your case, because you know that the image is valid despite the mismatched header, you can pass barebox_update the force flag -f, so it ignores the header check.
Another way is to update barebox over USB or over the network and use a pristine barebox image that hasn't been mangled by writing MBR magic over it.
Quoted from my answer over at https://www.linuxquestions.org/questions/linux-embedded-and-single-board-computer-78/image-is-not-of-type-arm-barebox-image-but-of-type-mbr-sector-update-failed-4175727785/