On 07/11/2010 06:31 PM, Peter Bako wrote:
quoted text
> I'm setting up (well, trying to I guess :-) ) a read-only OpenBSD system to
> run off a small CF card.  Never having done this before, I found an
> excellent article written by Daniele Mazzocchio
> (http://www.kernel-panic.it/openbsd/embedded/) to use as my guide.  I had a
> few minor issues crop up, but have been able to work my way through them.
> However I finally got to one that I am stumped with.
>
> Basically once I boot of my new image, I am able to log into it on the
> serial console and things look ok.  I can also ping the IP address of the
> unit, but when I try to SSH into it I get the following message:
>
>    "Server refused to allocate pty"
>
> I've checked over my setup and all seems fine as per the instructions.  I
> have all the pty* devices from /dev (which is RO) linked to /var/run/dev
> (which is in memory), so the problem cannot be that these devices are not
> writeable.  (Actually /var is linked to /tmp/var, where the /tmp directory
> is in memory and populated by the image from a directory called /template.)
>
> Unfortunately this goes a bit beyond my current skill set, so if anyone has
> any suggestions I really would appreciate the help.
>
> BTW, in case it matters.  I'm using OpenBSD 4.6 as both the host on which I
> setup the image and OS on the CF card.  The card in question is a 64M
> SanDisk CF and is being plugged into a Soekris Net4801 box.  None of these
> should make a difference, but you never know... :-)
>
> Thanks,
> Peter
>
You probably need your entire /dev directory in memory.  It worked that 
way for me.

But I'll tell you something from my own experience: I got this whole 
RO-flash, RW-on-MFS thing working on a Soekris net5501, but it was a big 
hassle -- a hassle that I would have to repeat on every upgrade.  I 
started with the link you mentioned, plus several others, and still had 
to work through several more issues myself (I had read plenty of, shall 
we say, admonitions on this list about not doing what I was trying to 
do, so I decided I needed to fix everything myself :).  Some of those 
issues didn't rear their ugly heads until several days after the initial 
install.

After much suffering, and reading this list and the experiences of many 
folks getting reasonable life out of modern CF cards (at least 
comparable to hard disks), I decided that a standard OpenBSD install was 
the way to go.  On my next snapshot install I did exactly that; it went 
much more smoothly.  The only real reason to do the RO-flash setup is to 
make the device "unpluggable with impunity", i.e., it will not have 
corrupt filesystems after a non-orderly shutdown (but you may of course 
still lose data on the MFS).  For me, unless I was making and selling 
these things to the unwashed public, even that is not worth the hassle 
of the RO-flash setup.  CF cards are cheaper than my time.  If you want 
to do it for the learning experience alone, then OK, but be prepared to 
do it mostly, if not all, yourself.  And once you do, or once you do an 
upgrade, I suspect you will want to go back to a standard install.

My $2.98 US, FWIW.

Corey