Configuring flow control for network interfaces

[John Baldwin]

I think it would be useful if we could pick a device-independent interface for 
configuring flow control on network interfaces, perhaps as media options via 
ifconfig.  I know that the msk(4) driver allows RX and TX flow control to be 
toggled via the link0 and link1 flags (the manpage for msk(4) needs updating 
on this topic I think).  I have a hack for work to disable TX flow control on 
cxgb(4), but it doesn't use flow control currently.  Is flow control ethernet-
specific?  If so, perhaps we could add two new flags for RX and TX flow 
control to the Ethernet-specific options in that case?  Do folks have other 
ideas?

-- 
John Baldwin