Herbert Graf(mailinglist4@farcite.net) is reported to have said:
> 
> On Fri, 2008-03-07 at 17:00 -0700, Robert Rolf wrote:
> > Why not modify your code to make the drive Read only, unless
> > some sort of 'unlock' sequence is executed? E.g. read last sector,
> > N-1, n-2, n-3 then n-3 n-2 n-1 N.
> > Something no O/S will do, but your 'unlock' program would.
> 
> Well, the fact is it's not a "real" drive, it just looks like one to the
> OS.
> 
> Nothing in my device is "writable", so I'm not concerned about the OS
> attempting to write stuff and it mucking up my hardware. The issue is
> because I don't have anything writable the OS gets confused when it
> writes something but then notices the copy on my "drive" doesn't match
> (I get dropped write page errors in dmesg). The most common occurance is
> updating the root directory entries with access times. So far it doesn't
> appear that these errors are an issue, things seem to work fine, but I
> am concerned that with the right software/hardware combination it will
> pop up as a problem.
> 
> How does a hard drive tell an OS it's write protected? Is it even
> possible?

What your looking for is in man 8 mount.

mount -r /dev/sda1

-r     Mount the file system read-only. A synonym is -o ro. 

Wayne

-- 
Programmers don't die, they just GOSUB without RETURN
_______________________________________________________
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist