Subject: Re: x & ioctls, & mount_union
To: Rick Hawkins <rhawkins@iastate.edu>
From: Paul Goyette <paul@pgoyette.bdt.com>
List: port-mac68k
Date: 04/24/1997 07:07:48
On Thu, 24 Apr 1997, Rick Hawkins wrote:

> And now that i think of it, these kernels that I've created have 
> also claimed not to support mount_union when i've tried it.
> 
> A couple of weeks back, wehn mount_union came up, creating myown 
> kernel was suggested.  But now that I look into GENERIC, it seems 
> that mount_union is supposedly already supported.  I've tried as 
> both "mount -t union" and "mount_union", with no success, both 
> under the sbc.28 and compiling my own.

Well, not only does your kernel need to support the mount_union stuff (via
the `option UNION' in your config) but the lower file system has to
support "whiteouts" (these enable the lower FS to "hide" things that exist
in the upper FS).  If your partition was mkfs'ed using the Mac-side
utility, it is an "old-style" ufs partition which doesn't support the
white-out feature.

You can upgrade the partition to a new-style one using (IIRC) the command
`mkfs -c' (c = convert, I guess).  But once you do this, you will not
beable to use the Mac-side utilities, since they don't undertsand the new
style partition.

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