Porting to a new unsupported board: uboot fails to properly read the partition table

Andrea Bernabei andrea.bernabei at canonical.com
Tue Dec 15 15:47:16 UTC 2015

On Tue, Dec 15, 2015 at 3:37 PM, Woodrow Shen <woodrow.shen at canonical.com>

> Hi,
> I wonder which board did you win to get ? :) Also, Is your board able to
> boot into Snappy successfully ?
> If yes, I think the partitions of image should be fine to work well.
> Before flashing image to SD card, you also can use `fdisk -lu
> /path/to/image` to check all the partitions.
> In my experiences of Snappy porting, I met a problem to break up the
> partitions generated by u-d-f,
> and I diff the hex between BSP image and Snappy. I found that u-d-f
> overwrote wrong the partition table
> due to bigger size of preloader binary, so I made the binary divide into
> two parts. Furthermore, The offsets
> also needed to be described in package.yaml in the OEM snap.
> The another interesting thing is that I need to make boot flag of 1st
> partition turn off, and then the board
> can boot to Snappy normally. XD
> This is my reflection, hope it can help you :)
Hi Woodrow,
thanks for getting back to me :)

I haven't had the time to write a post about it, though I managed to get
Snappy to boot successfully on my board
just a couple of days after my help request here :)
(for the record: the issue I reported here was due to a very dumb mistake
on my side: I was flashing on sdb1 instead of sdb, so it wasn't
actually overwriting the partition table that was already available on the

I have to say it has been quite easy, I was expecting porting to a new
board would have been much more difficult :)
I only had to patch and tweak u-boot, basically (and apply the apparmor
patches to the kernel, but that's almost automatic) :)

I should definitely post the modified bits so that others with the same
board can get Snappy, but
time is never enough :) It's on my TODO

PS: the board is a Toradex Iris + Colibr iMX6DL module


> Cheers,
> Woodrow
> On Fri, Nov 20, 2015 at 1:15 AM, Andrea Bernabei <
> andrea.bernabei at canonical.com> wrote:
>> Hello everyone,
>> I recently won a dev board at a conference, and I'm trying to port Snappy
>> to it as a spare time pet project (yeah, this is the kind of things I am
>> into :D)
>> I read the porting guide
>> https://developer.ubuntu.com/en/snappy/guides/porting/
>> and Ogra's post at
>> https://ograblog.wordpress.com/2015/01/25/porting-ubuntu-snappy-to-a-yet-unsupported-armhf-board/
>> I have already patched the kernel with the required apparmor patches and
>> also uboot to add ext4 commands, and I successfully installed them on the
>> board.
>> The problem I have at the moment is that the partition tablet of the
>> image created by ubuntu-device-flash (using my custom device tarball as
>> input) does not seem to be properly supported by uboot (and even some tools
>> like gparted).
>> Here's what a few tools report when listing the partitions on the
>> *sdcard*
>> (I tried both with a 32Gb and a 4Gb sdcard)
>> - uboot's "mmc part" reports just 1 partition, type 0c
>> - gparted only shows 1 big partition, like uboot, with unknown filesystem
>> and lba flag
>> - parted shows 4 partitions
>> - kpartx shows 4 partitions
>> Any advice?
>> Andrea
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