read-only root fs with Busybox?

Stephane Billiart stephane.billiart at
Mon Dec 12 06:38:37 UTC 2005

On 08/12/05 ? ? 18:07, Jessee, Mark wrote:
> Hi,
> I'm attempting to setup a read-only root filesystem on a Compact Flash card.

That's also what I have been doing for quite some time now.

> Do I need to add an entry in /etc/fstab for '/' to allow the mount command to
> work properly? Does this work alongside the GRUB parameters? Or does adding an
> entry for '/' in /etc/fstab with the 'ro' option mean I no longer need to pass
> 'ro' in GRUB?
> Why does 'cat /proc/mounts' give 2 entries for '/' with 'rootfs' being 'rw'?

Personnally, I use LILO and my /etc/fstab has no entry for '/'.
Like you, I have a rootfs partition which is mounted rw, I don't have
an explanation for this but I don't think it is an issue.

sokdist# cat /etc/fstab 
proc    /proc           proc    defaults 0 0
devpts  /dev/pts        devpts  defaults 0 0
sokdist# cat /proc/mounts 
rootfs / rootfs rw 0 0
/dev/root / ext2 ro,nogrpid 0 0
none /proc proc rw,nodiratime 0 0
none /sys sysfs rw 0 0
none /var tmpfs rw,noexec 0 0
none /dev/pts devpts rw 0 0
usbfs /proc/bus/usb usbfs rw 0 0

> Any tips on the correct configuration for a read-only root fs with support for
> remounting read-write?

Here is what I use to remount rw/ro at will

mount -o remount,rw,noatime -n /dev/root /
mount -o remount,ro -n /dev/root /

Stéphane Billiart            

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