Re: kern/51531: Recent networking regression affecting installs

[Joerg Sonnenberger <joerg%bec.de@localhost>]

The following reply was made to PR kern/51531; it has been noted by GNATS.

From: Joerg Sonnenberger <joerg%bec.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
	netbsd-bugs%netbsd.org@localhost, Andreas Gustafsson <gson%gson.org@localhost>
Subject: Re: kern/51531: Recent networking regression affecting installs
Date: Wed, 5 Oct 2016 17:07:34 +0200

 On Wed, Oct 05, 2016 at 02:45:01PM +0000, Andreas Gustafsson wrote:
 > The following reply was made to PR kern/51531; it has been noted by GNATS.
 > 
 > From: Andreas Gustafsson <gson%gson.org@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: kern-bug-people%netbsd.org@localhost,
 >     gnats-admin%netbsd.org@localhost,
 >     netbsd-bugs%netbsd.org@localhost,
 >     gson%gson.org@localhost (Andreas Gustafsson)
 > Subject: Re: kern/51531: Recent networking regression affecting installs
 > Date: Wed, 5 Oct 2016 17:42:18 +0300
 > 
 >  Roy Marples wrote:
 >  >  I think ifconfig -w 15 -W 5 should be added to sysinst before the ping
 >  >  test to wait for DaD to clear.
 >  
 >  I think sysinst, and other existing code that configures IP addresses,
 >  is not incorrect as written, and should not be required to do this.
 
 I disagree, quite a bit. There are three options for such a program:
 (1) It is dumb and just expects a newly configured interface to work
 after some time. Nothing new here.
 (2) It tries to be smart and checks immediately after configuration if
 ping works. This has been wrong for a variety of network conditions
 already, since link configuration itself can already take time in the
 second range. WiFi can be even worse with slow authorisation. This
 really is an application bug and not related to this issue at all.
 (3) It tries to be even smarter and checks for link state changes before
 ping. This still doesn't work properly for WiFi or 802.1x ports. DaD
 timeouts are no different here.
 
 In short, *any* assumption that a freshly configured network interface
 is going to be ready RSN are wrong. There are some architectural issues
 in that we currently have no way to report "this interface should be
 usable now", which is shared with all the BSDs. But it is essentially
 unrelated to the recent DaD changes.
 
 Joerg