On Fri, Jun 08, 2001 at 10:10:10AM -0400, Joseph Sarkes wrote:
> I also recall various problems in the further past with 
> the union filesystem. Is union filesystem stable enough
> now to have a read only source tree? 

  I've been doing builds this way for about 6 years.  It works very well.
There has recently been breakage if the lower layer is on NFS but with FFS
it works fine.  It's possible that that problem has been fixed---I haven't
tried it lately.

> If only under certain conditions, what are they? I remember 
> being able to blow it up (union fs) by some method that I 
> don't recall at this particular moment.

  There was a potential for a crash if you modified the lower layer while
the upper layer was active (e.g., during a build).  I don't really know if
that has been fixed, but since it wouldn't make sense to be updating your
source tree while building in the upper layer, it's not much of a limitation.