Why would NFS-mounted rootfs be "read-only"?

[EdSutter]

I have been in the process of reworking the SABRESD linux to run on our custom hardware.

I have been primarily runing with my rootfs NFS-mounted and that has been fine.

Something has changed that has caused my board to boot up with rootfs now read-only.

I have no idea what caused this to change.

My /etc/exports file entry for this is:

/Full_path_to_my_rootfs_directory/my_rootfs *(rw,no_root_squash)

I've run exportfs -a, and my kernel command line is:

console=ttymxc0,115200 ip=dhcp root=/dev/nfs nfsroot=${serverip}:/Full_path_to_my_rootfs_directory/my_rootfs,v3,tcp

Then at bootup, I see this message:

VFS: Mounted root (nfs filesystem) readonly on device 0:11.

I am able to log in however, everything is readonly.

This used to work.

Same server, same client, nothing obvious (related to NFS) has changed.

Any idea what might cause this?

[EdSutter · Accepted solution]

Got the answer at linuxquestions.org...

Apparently my previous kernel defaulted to a read/write mode for nfs-mounted rootfs,

but this kernel does not.  Adding "rw" to my kernel command line fixed this.

So the full command line is:

console=ttymxc0,115200 ip=dhcp root=/dev/nfs nfsroot=${serverip}:/Full_path_to_my_rootfs_directory/my_rootfs,v3,tcp rw