Re: Slow transmission with Marvell SKnet

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Sun, Aug 13, 2017 at 03:13:52PM +0200, Frank Wille wrote:
> Robert Swindells wrote:
> 
> > What is the output of:
> >
> > # ifconfig -m sk0
> >
> > You could also try running the sk0 as autoselect, both with the test
> > machines and the switch.
> 
> Thank you very much! I fixed the problem! It was probably my fault.
> 
> Explanation: I know that the GBit-mode requires much more energy than 100
> MBit, so I always tried to limit the interfaces to 100 MBit. The 8241 CPU
> is not capable to exceed the full 100 MBit bandwidth anyway.

I think -- I'm not certain -- that when we select a particular link
configuration we then disable autonegotiation.

In the modern era, this is a bug!  There is no way for our link partner
to know what we did unless it too is explicitly configured to disable
autoneg (some modern link partners can't even be configured that way).

What we should do is what everyone else does: leave autoneg enabled, but
advertise, and accept, only the single mode the user asked for.  Then it
would work how you expect and there would be, in particular, no duplex
mismatch between the two sides of the link, which is what caused your
problem.

Thor