[Buildroot] readonly rootfs problem

[Baruch Siach <baruch@tkos.co.il>]

Hi Ed,

On Mon, Mar 03, 2014 at 05:14:47PM -0500, Ed Sutter wrote:
> I've been using buildroot to create my rootfs for a few months.
> I build my kernel directly out of freescale.git.
> I had been running with my rootfs nfs mounted, and all was well.
> Recently I had spent some time with a ramdisk-based rootfs because
> i was working on some kernel stuff.
> Now I'm going back to running rootfs/nfs and I'm finding that
> it "insists" on coming up in read-only mode.
> 
> I was initially using buildroot-2013.08, and recently I
> updated to buildroot-2013.11; however, I don't think that has
> anything to do with this.  As far as I can tell I have everything
> set up properly...
> 
> ####On NFS host /etc/exports has...
> /full_path_to_my_rootfs *(rw,no_root_squash)
> 
> ####On target...
> /etc/inittab...
> null::sysinit:/bin/mount -o remount,rw / # REMOUNT_ROOTFS_RW
> 
> /etc/fstab...
> # /etc/fstab: static file system information.
> #
> # <file system> <mount pt>     <type> <options>         <dump> <pass>
> /dev/root       /              ext2     rw,noauto         0      1
> proc            /proc          proc     defaults          0      0
> devpts          /dev/pts       devpts   defaults,gid=5,mode=620 0      0
> tmpfs           /dev/shm       tmpfs    mode=0777         0      0
> tmpfs           /tmp           tmpfs    defaults          0      0
> sysfs           /sys           sysfs    defaults          0 0
> 
> Output from mount:
> # mount
> rootfs on / type rootfs (rw)
> 1.2.3.4:/full_path_to_my_rootfs on / type nfs (ro,relatime,vers=3,rsize=4096,wsize=4096,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=1.2.3.4,mountvers=3,mountproto=tcp,local_lock=all,addr=135.222.138.108)
> devtmpfs on /dev type devtmpfs
> (rw,relatime,size=110708k,nr_inodes=27677,mode=755)
> proc on /proc type proc (rw,relatime)
> devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)
> tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777)
> tmpfs on /tmp type tmpfs (rw,relatime)
> sysfs on /sys type sysfs (rw,relatime)
> 
> I actually think the problem is in the kernel, not the rootfs.
> I say this because even some of my older rootfs copies (still on my
> host) are now
> showing up as read only.  The bootlog always ends up with this message:
> VFS: Mounted root (nfs filesystem) readonly on device 0:11.
> 
> Any idea what I might be doing wrong here?

What happens if you manually run:

	mount -o remount,rw /

Do you see any error message?

baruch

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