[SOLVED] Can no longer use Fedora NFS to boot remote device

[17twenty]

I have a development board connected over ethernet such that my desktop is 10.0.0.1 and my dev board is 10.0.0.3.

The remote device is set to boot from an NFS share and the kernel is told as so:

console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=10.0.0.1:/home/nick/Dev/git-rootfs ip=10.0.0.3:::::eth0,nfsvers=3

I booted my desktop this morning after applying updates before shutting down last night and tried to start it all up this morning. Sadly my board hangs with the following:

[  108.951477] VFS: Unable to mount root fs via NFS, trying floppy.
[  108.958831] VFS: Cannot open root device "nfs" or unknown-block(2,0)
[  108.965606] Please append a correct "root=" boot option; here are the available partitions:
[  108.996002] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

I've checked that /etc/export hasn't been broken which reads as follows:

/home/nick/Dev/git-rootfs	*(rw,sync,no_subtree_check,no_root_squash)

but I did notice that if I try and mount the nfs share locally it also fails:

[nick@slimtop tftpboot]$ sudo mount -v  10.0.0.1:/home/nick/Dev/git-rootfs /media/
mount.nfs: timeout set for Thu Jul  5 11:06:59 2012
mount.nfs: trying text-based options 'vers=4,addr=10.0.0.1,clientaddr=10.0.0.1'
mount.nfs: mount(2): Permission denied

I can make this work by issuing:

sudo mount -v -o vers=3 10.0.0.1:/home/nick/Dev/git-rootfs /media/

But I have no idea on how to do the same to the kernel - I thought specifying the version with nfsvers would work but I can't find a changelog for the nfs-utils that would explain what's broken/changed.

Any ideas?

[stevea]

NFS version 4 is now the default, but your only supports v3 I think. Not clear why you get permission denied.

According to the kernel docs, the nfs options go on the nfsroot= parameter, not the ip= one.
Like this ...

console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=10.0.0.1:/home/nick/Dev/git-rootfs,nfsver=3 ip=10.0.0.3:::::eth0

So I imagine the kernel is trying to mount nfsv4 and failing b/c you didn't spec the version correctly.


Maybe try the nfsrootdebug kernel parameter too if the above fails to help.

[17twenty]

Hey Steve,

I'm not sure if that ordering made a difference but I managed to get it working with a reboot (desktop and board) and changing the boot parameters to:

console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=10.0.0.1:/home/nick/Dev/git-rootfs,ver=3 ip=10.0.0.3:::::eth0

I also had to redisable iptables using:

systemctl stop iptables.service
systemctl disable iptables.service

Not sure if that will help anyone - I got a bit desperate as I hate wasting time on things that break for no real reason so lots of things were tried as a hail mary move!.

Thanks for the reply though - it helped me focus a bit on what it could be.