[yocto] devtmpfs failing to mount

[Loïc Domaigné]

> > > I'm using Yocto version rocko with a custom layer to run on the Zynq+ SoC
> > > on a custom board. When trying to boot I'm getting the following error in
> > > the boot output:
> > > ...
> > > [    4.127997] EXT4-fs (mmcblk0p2): couldn't mount as ext3 due to feature
> > > incompatibilities
> > > [    4.183737] EXT4-fs (mmcblk0p2): recovery complete
> > > [    4.190840] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data
> > > mode. Opts: (null)
> > > [    4.198870] VFS: Mounted root (ext4 filesystem) on device 179:2.
> > > [    4.205861] devtmpfs: error mounting -2
> > >
> > > Are there common reasons for this happening I should check?
> >
> > Not sure if that helps, but I'd check:
> > a) What's the type of the mmcblk0p2 (=rootfs?) partition?  and
> > b) How is this partition mounted?

> Yes those are both useful things to know. I am booting by flashing an SD
> card with a wic image (made using sdimage-bootpart.wks), so the flashing
> process takes care of creating the partitions. So the partition should be
> of type EXT4. The mounting process is actually what I'm a little fuzzy on
> in the first place.

I am not familiar with the meta-xilinx layer yet.
>From what I can read/understand:
- is mmcblk0p2 the rootfs? 
  If so: this partition should get mounted at kernel boot using the
  "root=..." boot arg. This, in turn, is set by "Das uboot" bootloader.
  I guess all the glory details can be found in the
  u-boot-zynq-uenv.bb recipe or similar. 
- if mmcblk0p2 is not the rootfs, this must be mounted somewhere. A 
  casual place to look at would be /etc/fstab. 

Is there a /etc/fstab available on your system?

Cordialement,
Loïc