[Oberon] Ethernet adapters, PIO and DMA

peasthope at shaw.ca peasthope at shaw.ca
Thu Aug 5 18:51:18 MEST 2010


This is a suggestion for a small improvement in 
documentation of support for Ethernet cards in ETHNO.
Might also be relevant to A2.

According to the answer to 
http://people.freebsd.org/~wpaul/3Com/README , 
Q: "What's the difference between the xl driver and the vx (vortex) driver?",
3C509 adapters support PIO but not DMA whereas the 3C905 
adapters support both PIO and DMA.  From a cursory look, 
Net3Com90x.Mod is written to use DMA only.  There is no 
option to use PIO on a 3C905 card with the extant driver(?).

A factor in using these cards appears to be that some early 
Pentium system boards would not support DMA.  My case is an 
ASUS SP97-V board.  A 3C905B Ethernet card on the SP97-V board 
has not worked.  Presumeably it would work if the Net3Com90x.Mod 
driver could make use of PIO rather than DMA.

So I request or suggest addition of a note in this page under 
At least state that the 3C509 uses PIO and not DMA.
Also, assuming I am correct, that Net3Com90x.Mod supports 
DMA but not PIO.

Would also be nice to elaborate a little on the question of 
the system board supporting DMA.  It is relevant to more 
peripherals than Ethernet.  Is it true that there were boards 
which did not support DMA?

Thanks,           ... Peter E.

Carnot netboots *.SUN4C; installation of NetBSD 5 pending.
Personal site works;  http://members.shaw.ca/peasthope/ .

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