pppoe(4) and PPP_TERM_UNKNOWN_SESSIONS

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

While working on the recent modularization of the pppoe(4) driver, I 
noticed that the PPP_TERM_UNKNOWN_SESSIONS option really controls very 
little code.  For the modular version of the driver, I turned this code 
on always, and for both modular and built-in versions, I added a new 
boolean sysctl variable 'net.pppoe.term_unknown' to actually enable 
termination of the unknown sessions.

It was suggested on irc/icb that perhaps this code should be included in 
all versions of the driver, built-in as well as modular, without having 
to specify 'OPTIONS PPP_TERM_UNKNOWN_SESSSIONS' in the kernel config 
file.  This very easy to do, but there are a couple of caveats that give 
me slight pause:

1. Compiling in this code adds a few bytes of memory to the softc for
   each pppoe device instance (unit).
2. More importantly, for each received packet, the driver needs to copy
   the source Ethernet address.

#1 doesn't bother me much, but #2 is per-packet performance hit.  It
probably isn't really significant on most platforms, but some embedded 
systems (or antiquated hardware!) might notice.

So, I soliciting input on whether to retain the config option, or remove 
the option completely, relying only on the sysctl variable to control 
session termination.

Comments?



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| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
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