read-only filesystems

Kevin D. Clark kclark at CetaceanNetworks.com
Wed Mar 19 13:38:33 EST 2003


John Abreau <jabr at abreau.net> writes:

> kclark at CetaceanNetworks.com (Kevin D. Clark) writes:
> 
> > But then I get to /dev.  How to handle /dev?  Some of the stuff under
> > /dev needs to be writable.
> 
> Have you actually tried running it and it failed, or are you just assuming 
> that /dev must be on a writeable filesystem? 

Yes, I've tried it, and yes, it fails, for a number of reasons.

For example, it seems like the mingetty processes are dying, probably
because they can't chown the ttys that they are attempting to handle.

> The thing is, files under /dev are not regular files, they're actually 
> just a mapping of kernel device drivers onto filesystem semantics. So the 
> read-only state of the filesystem shouldn't be relevant to their 
> function, since writing to a device file doesn't actually write to 
> the filesystem it resides in. 
> 
> It does mean that you won't be able to, for example, chown the audio 
> device
> when a user logs in on the console. However, if you chmod the audio 
> device so it's world-writeable before you make the filesystem read-only, 
> then it should work fine. 

I guess I was hoping to solve this problem all at once instead of
perhaps having to come back to it later on, i.e. to not have to deal
with making the next /dev/whatever file world writeable when the
situation comes up.

Hmm.  I suppose that I could try making the /dev/tty* file world
writeable.  I'll try that soon and let you know how it works.

Thanks,

--kevin
-- 
Kevin D. Clark / Cetacean Networks / Portsmouth, N.H. (USA)
cetaceannetworks.com!kclark (GnuPG ID: B280F24E)
alumni.unh.edu!kdc




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