Image is not of type ARM barebox image but of type MBR sector, update failed

Ricky12 · 08-06-2023, 02:29 PM

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:

Code:

barebox_update -t nand /dev/mmc0.barebox

I get following error:

Quote:

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:

Quote:

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:

Code:

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?

Emerson · 08-07-2023, 06:50 AM

Code:

of=/dev/<DEVICE>

This looks suspicious to me. What device? You may be putting this image to a partition, this would explain why boot sector is untouched.

Ricky12 · 08-07-2023, 07:01 AM

Well, I am writing as of=/dev/sdb .
These are the partitions, whereby my SD Card is D:

Code:

wwwri@LAPTOP-HO38O9KH /cygdrive/c
$ cat /proc/partitions
major minor  #blocks  name   win-mounts

    8     0 500107608 sda
    8     1    266240 sda1
    8     2     16384 sda2
    8     3 498799616 sda3   C:\
    8     4   1024000 sda4
    8    16  62334976 sdb
    8    17     26624 sdb1   D:\
    8    18    371800 sdb2

Emerson · 08-07-2023, 07:29 AM

I do not know anything about this Windows business, will be 19 years this fall without MS for me.
Anyhow, your SD card is not D, the first partition of sdb is marked as D. Considering the error you are getting I bet you are writing to sdb1.

Ricky12 · 08-07-2023, 07:47 AM

When I use

Code:

dd if=phytec-qt5demo-image-phyboard-mira-imx6-3.sdcard  of=/dev/sdb bs=1M conv=fsync

embedded board still boots, but barebox can not be updated.
With

Code:

of=/dev/sdb1

instead of

Code:

of=/dev/sdb

embedded board does not boot.

Emerson · 08-07-2023, 08:11 AM

Quote:

... barebox can not be updated.

Seems like a separate issue.

a3f · 08-10-2023, 10:05 AM

Quote:

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:

Code:

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.

Quote:

When I stop autoboot of embedded board and try flashing barebox like this:

Code:

barebox_update -t nand /dev/mmc0.barebox

Code:

 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.