Re: Question about dev.fxp.0.noflow

On Wed, Dec 19, 2007 at 04:33:44AM +0300, Andrey Chernov wrote:
 > Does anybody know why dev.fxp.0.noflow=1 by default?
 > Is it more proper to set it to 0? (by default or via /etc/sysctl.conf)
 > 

Since flow control is valid only when link partner also agrees on
advertised pause capability on full-duplex media, it needs more work
in mii/phy driver to advertise correct pause capability. It also needs
a way to pass negotiated pause capability back to drvier such that
each drvier should program necessary flow control parameters depending
on its MAC capability and negociated ones. Just enabling flow control
on one side have no effect.

I think FreeBSD needs an architectural way to handle flow control in
mii layer. Both NetBSD/OpenBSD already supports flow control and
marius_at_ is working on it. Last time I tried his patch seems to work.
I don't know when it would hit the tree but I guess it will happen
in near future. If we have generic flow control code in mii we can
easily add flowcontrol support code to each driver. You may no longer
need to set such obscure knob.

-- 
Regards,
Pyun YongHyeon