SheevaPlug boot error “can't open root device”

["Diogo B." <db7%demux.eu@localhost>]

Dear mailing list,

I'm trying to revive an old SheevaPlug device. Luckily, I've found NetBSD supports it. SheevaPlug has a Marvell Kirkwood CPU (ARMv5TE), an SD card slot, a USB port, and an Ethernet port. Serial output is available via a secondary USB port.

Getting the pre-built kernel to boot the SheevaPlug was quite straight-forward. Unfortunately, the boot process stops with the following error:

    [   2.5099662] root on sd0a dumps on sd0b
    [   2.5099662] vfs_mountroot: can't open root device
    [   2.5099662] cannot mount root, error = 6

I haven't worked with NetBSD before, so my issue is probably very simple to solve. Let me quickly explain what I have done.

1. Downloaded all pre-built NetBSD 10.0 sets for evbarm.
2. Partitioned an USB stick in two partitions: one 3GB partition (ext2) and
   1GB swap. I'm configuring this from a standard Ubuntu workstation, I
   don't seem to have support to format the partition with UFS/FFS.
3. Uncompressed all the sets (base.tgz, debug.tgz, etc) and kern-SHEEVAPLUG.tgz
   in the first partition of the USB device. I have done no further changes
   to the partition, no change in the configuration whatsoever. I am guessing
   that running `postinstall` once I get it booted will do the job, but I've
   never installed NetBSD before, so it's just a guess.
4. Started SheevaPlug and entered the following in the uboot prompt:
    env default -f # clean up uboot environment
    setenv kernel_addr 0x2000000
    setenv kernel_file netbsd.ub
    ext2load usb 0:1 ${kernel_addr} ${kernel_file}
    bootm ${kernel_addr}

After that, the system boots up to the point a prompt asks me for a root device, a dump device and the file system. It seems to support ext2, so I don’t understand what the issue is. (I don’t know what the dump device is, should I have a partition for that?)

Here is a more complete output:

    [   2.4299624] umass0 at uhub0 port 1 configuration 1 interface 0
    [   2.4299624] umass0: 6989 (0x24a9) Intenso Ultra Line (0x205a), rev 2.10/2.00, addr 2
    [   2.4499718] scsibus0 at umass0: 2 targets, 1 lun per target
    [   2.4499718] sd0 at scsibus0 target 0 lun 0: <Intenso, Ultra Line, > disk removable
    [   2.4499718] sd0: fabricating a geometry
    [   2.4499718] sd0: 117 GB, 120000 cyl, 64 head, 32 sec, 512 bytes/sect x 245760000 sectors
    [   2.4499718] sd0: fabricating a geometry
    [   2.4899680] boot device: sd0
    [   2.4999683] root on sd0a dumps on sd0b
    [   2.5099662] vfs_mountroot: can't open root device
    [   2.5099662] cannot mount root, error = 6
    [   2.5099662] root device (default sd0a):
    [   2.5099662] dump device (default sd0b): ?
    [   2.5099662] use one of: ld0[a-p] sd0[a-p] none ddb halt reboot
    [   2.5099662] dump device (default sd0b):
    [   2.5099662] file system (default generic):
    [   2.5099662] root on sd0a dumps on sd0b
    [   2.5099662] vfs_mountroot: can't open root device
    [   2.5099662] cannot mount root, error = 6

I've tried playing around with the options available (eg, setting the file system to ext2fs instead of generic), but I am basically stuck.Also, I’ve tried using an SD card instead of the USB stick, but it gave me the same results (the device is called ld0 instead of sd0).

Does anybody have a tip for me on how to fix or debug this? I haven't set any bootargs in uboot. Is there any argument I should pass to the kernel when starting bootm?

Thank you.

Regards,
-Diogo