Thank you for your reply Hubert. I will forward this question
to the tech-kern list

Hubert Feyrer <hubert@feyrer.de> wrote on 09/24/2005, 01:48:16 AM:
> 
> On Sat, 24 Sep 2005 jerry@evasefor.com wrote:
> > Good afternoon list,
> > I have an SBC with 2 cpu each running their own netbsd kernel:
> >
> > PHY--CPU1-----------logic---------CPU2---PHY
> >            mii bus         mii bus
> >
> > after I'm done processing a packet on CPU1 how can I address it
> > to CPU2? Is there a kernel level interface to the MII bus I could
> > use for this (i.e read/write)? Or any other idea, like shared memory,
> > anything that you think could work?
> 
> As far as I understand, NetBSD can attach ethernet drivers to the MII bus 
> using the "phy" interface. Maybe the (software) interfaces used there are 
> useful for you?
> 
>  	ex0 at pci2 dev 1 function 0: 3Com 3c905CX-TX 10/100 Ethernet with mngmt (rev. 0x40)
>  	ex0: interrupting at irq 7
>  	ex0: MAC address 00:26:54:10:11:d4
> ===>	ukphy0 at ex0 phy 2: Generic IEEE 802.3u media interface
>  	ukphy0: OUI 0x0010a9, model 0x0012, rev. 1
>  	ukphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
> 
> See mii(4) for a bit more data. And the various drivers mentioned in 
> there, and of course their source (probably in src/sys/dev/mii).
> 
> I'm not competent to talk about either the MII bus or the driver 
> infrastructure though. I think asking that on tech-net or tech-kern may 
> get you better answers, this is not really specific to embedded 
> technology.
> 
> 
>   - Hubert