On marted=EC 15 maggio 2007, Valentin Quequet wrote:
> Hi group,
> I'd like to thank you for your answers to my previous post related to
> UML and hostfs.
> While you were thinking over my problem, I was investigating that
> matter too, trying again and again to follow the instructions in the bold
> section " hostfs as the root filesystem " of the web page at
> What I must say before you read further is that these instructions are
> good and up-to-date, contrary to my believing they were obsolete. But I
> must warn you: IT IS STILL WORTH reading further ;-)
> Finally, and like you will most likely do, I screamed when I realized
> that it was because of ~some kind of complexity~ that my UML refused to
> boot. The counterpart is that I now have clues on this thing I will call a
> Amongst the few configurations I ran, only one failed; let me describe
> I typed as root:
> 0) # mkdir /root/SomeEmptyDir /root/Filesystem_RO /root/Filesystem_Di=
> /root/Filesystem 1) # mount -t ext3 -o loop,ro,noatime
> /root/Filesystem.ext3 /root/Filesystem_RO 2) # mount -t unionfs -o
> dirs=3D/root/Filesystem_Diff=3Drw:/root/Filesystem_RO=3Dro unionfs
> /root/Filesystem 3) # linux hostfs=3D/root/SomeEmptyDir root=3D/dev/root
> rootflags=3D/root/Filesystem rootfstype=3Dhostfs
> And UML or init hanged:
> Initialized stdio console driver
> Console initialized on /dev/tty0
> Initializing software serial port version 1
> Failed to open 'root_fs', errno =3D 2
> VFS: Mounted root (hostfs filesystem) readonly.
> line_ioctl: tty0: ioctl KDSIGACCEPT called
> INIT: version 2.86 booting
> < --- UML or INIT Hangs --- >
> 1) Why VFS/hostfs failed to mount hostfs as root in read-write mode?
You must supply the 'rw' flag to change the default behaviour to mount=20
read-only. That is the default because most distributions call fsck before=
remounting in read/write mode.
> 2) Why a hang HERE of UML or Init?
Hmm... try adding init=3D/bin/sh to check whether UML boots fine or not. If=
that boots, you can try seeing whether subsequent actions work or not...
> What's wrong? Is it a bug of UML/hostfs or unionfs?
It could be in the init scripts run on such a configuration.
> Any suggestion? Any thesis is welcome.
> Note: I use standard up-to-date Debian GNU/Linux 4.0 (Etch release, stable
> branch) packages, except for the host kernel I've just patched with their
> skas patch, thought I have the same problem with their stock kernel. Both
> host and guest kernels are linux-2.6.18 debian flavours.
Testing more recent UML kernels may help.
Inform me of my mistakes, so I can add them to my list!
Paolo Giarrusso, aka Blaisorblade