[9fans] Re: Plan 9 from Bell Labs - Frequently Asked

[G. David Butler gdb@dbSystems.com]

>>as i mentioned in a previous message i still have problems with the
>>905 so i'm interested in any other experiences with it.
>
>I'm trying to get it to work reliably too.  I don't have the
>right documentation for PCI to know how to set the busmaster bit
>or to set the latency timer as specified by the errata.
>Can you help here?

I think I have that part down now.  After GlobalReset I do a
pcicfgr, set busMaster in command, set latency to 0xff and
do pcicfgw to 0x04 for a length of 12.

Now I get MasterStatus flag masterAbort at every transfer.

For the fun of it, I tried to use the DMA at transmit as well
as receive.  First I PIOd enough data to keep the transmitter
from underrunning then turned on the DMA.  Next, to make sure
the DMA code was sane, I memmoved the packet to a local buffer
with the preamble in front and DMAd the whole thing.  I always
get masterAbort!  I think I would only use the DMA on transmit
for gigabit ethernet though.  Is it possible to get underflow
with PIO at 100mb with current hardware?

So, any ideas about the abort?

David Butler
gdb@dbSystems.com