Subject: kern/7686:
To: None <>
From: Ian Dall <>
List: netbsd-bugs
Date: 06/01/1999 07:50:54
>Number:         7686
>Category:       kern
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun  1 07:50:00 1999
>Originator:     Ian Dall
>Release:        <NetBSD-current source date> 1.4C
System: NetBSD 1.4C NetBSD 1.4C (SIBYL) #1: Tue Jun 1 15:34:02 CST 1999 pc532

Heavy use of union file system produces a panic with the message: union: missing upper layer in write
I have a large body of code (83M, the mozilla M5 snapshot) in a directory
mozilla-dist. mozilla is a directory for local modifications. The mount
command is mount -t union -o -b mozilla-dist mozilla.

cd to the mozilla directory. Then do

  find . -name \*.[ch] | xargs grep nsHTMLButtonFrame

(the grep string is unimportant).
panic: union: missing upper layer in write