Boot disk read-only?

[Sam Zehr]

Hello all.

 

I apologize if this is the wrong place to ask, but I've had good luck with
USB questions in the USB list, so I thought this would be the place.

 

How do I make a disk in FreeBSD 9.0 _completely_ read-only?

 

I am converting an embedded system using flash for a disk from BSD 7.0 to
9.0

 

rc.initdiskless is working

 

I had luck with BSD 7.0 by doing the following additional steps:

1. Add noatime to fstab options

2. Add vfs.nfs.diskless_valid=1 to /boot/loader.conf

 

So far this is not working on BSD 9.0. It looks like something is changing
on the disk during boot

 

The disk is a USB thumb drive

 

Sysctl vfs.nfs.diskless_valid returns 0 once booted up

 

Please note that I am not just concerned about files - the entire disk needs
to be locked, like ROM.

 

Is there a way to completely lock the disk, even during the boot?

 

Or perhaps a reason why setting vfs.nfs.diskless_valid=1 in
/boot/loader.conf does not appear to work?

 

Thanks

Sam