Bug#610752: Make the link detection timeout preseedable
With the closing of #414117, we've introduced a more robust method of
detecting which network interfaces we want to configure have link. This is
required because link autonegotiation (and other associated shenanigans like
802.1X authentication) can take some time.
The problem is, the Ethernet spec is fairly quiet on the subject of
precisely how long we need to wait. Based on a bit of testing, the value of
"3 seconds" for the wait time has been set as the default -- currently a
hardcoded value in the NETCFG_LINK_WAIT_TIME #define (netcfg.h).
The outcome of this bug report is to allow this value to be preseedable.
Things that need to happen:
* A dummy template needs to go into debian/netcfg-common.templates to
register the debconf variable (I'm thinking netcfg/link_wait_timeout)
* netcfg_link_detect() needs to use debconf_get to retrieve the value of
this variable, turn it into an integer, and use it in place of
* All traces of NETCFG_LINK_WAIT_TIME can then be eradicated
* The installation manual appendix on available preseedable options must be
updated to include this variable, with some meaningful documentation.