This variable nominates the "upper" filesystem for an overlay mount.
This will be accessed read-write and it constitutes the "private"
files of the subhost.
-
++
If UPPER is different from LOWER, then the root file system is set up
as an overlay mount. In that case WORK (below) must be defined as a
directory outside of but on the same mount as UPPER.
-
++
If UPPER is the same as LOWER, then the subhost root filesystem is not
setup as an overla. Rather it is set up as a bind mount, if UPPER is
different from LIVE, or just as a pre-mounted LIVE filesystem.
This variable tells which services should be started on the
overlay-boot startup. The default value is +networking ssh+.
-
++
Note that if no services are started, then +overlay-init+ starts a
+dummy_service+ so as to keep +/.reaper+ from running out of child
processes, as it otherwise will exit and thereby terminate
./opt/subhost/mta/mta.conf
****
+----
BASE=.
-START= rsyslog newtorking ssh postfix
+CABLES= =
+START= rsyslog networking ssh postfix
+----
****
The above example assumes a directory +/opt/subhost/mta+ that contains
the configuration file +mta.conf+ and directories +root+, +work+ and
+live+. *overlay-boot* will set up an overlay mount on +live+ with
+root+ as UPPER, +work+ as WORK and +/+ as LOWER, i.e. an overlay of
-the main host filesystem.
+the main host filesystem. Further, the running subhost will feature a
+virtual cable to the main host, where the subhost end is named +eth0+
+and the main host end is named +mta0+, and upon start, an +ifup mta0+
+is attempted at the host end while the subhost end is handled via its
+neworking service.
+
+