[tulip] Only 1 port on a 21143 Quad.

Donald Becker becker@scyld.com
Thu Jun 13 13:33:01 2002

On Thu, 13 Jun 2002, gemorga2 wrote:

> Hmm, this product is interesting.  I was almost tasked at work to make
> exactly that product.  This was over 4 yrs ago.  Guess someone finally
> decided to make one.

There are several similar product, notably ones based on the rtl8139 and
winbond-840 with repeaters.
The design is really only suitable for a small office where switching
off the server makes all machines unusable anyway.

> Oh, and yes a "proper" 4 port card needs a MAC (21143 is a single port
> PCI to 10/100 Ethernet Media Access Controller (MAC)) for each
> ethernet port.  Alas, we just recently discussed that a there is
> silicon available that has 4 ethernet MAC chips combined into a single
> chip.  I doubt this was ever done for the Tulip design though.

There was a Digital 21140-series datasheet that described such a chip.
>From all I've heard, only the datasheet made it out the door.  The chip d

> A driver may get confused and think that there is more than one
> Ethernet interface on this card since there may be a second PCI
> "device" on the board for custom configuration of the switch ports
> (assuming there is some amount of management on the card for the
> switch).

I'm guessing that the switch is unmanaged, and without statistics.  It's
possible that all four external transceivers are controllable through
the serial MII management interface.  If so, running mii-diag eth0 -p
<PHY> should work properly.

If the switch chip does gather statistics, the 21143 GPIO or EEPROM pins
might be used as a serial (I2C or SMBus) bus to read them.  But that's
should be needed to get the board to work.

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993