[ECOS] 82559 in full duplex mode ??

[John Gumb <JGumb at Ridgeway-Sys dot com>]

Folks,

I've been trying some remote debugging over ethernet using insight with a PC
target. Things kind of worked but after a short while I'd lose my
connection, typically afer requesting a lot of data back from the target
(eg. requesting insight open up a large structure in a watch window or
something). Sometimes, I'd just lose the link on stepping. Damn shame when
you're used to serial debugging and finally you think you've got a decent
link...

Must say though, I do like insight. It's growing on me. Thought I was a
dyed-in-the-wool command line gdb person especially after working with IDEs
which seem to cripple rather than enhance command line gdb. That may change.

On a purely speculative note, I turned on 82559 ethernet chatter to see how
the link was being negotiated (or more precisely check it was being
auto-negotiated to 100MBit/sec FDX as I'm running into a netgear switch).
This was indeed the case - so I decided to drop back to 100Bit/sec Half
duplex just to see if it made any difference by running into a cheapo 3COM
hub. Sure enough, things seem to work better. I wouldn't say it's cast iron
yet - I'd need to run with it a bit longer but it's certainly more usable.

[digression. Actually, it was a bit more than speculative as we've written a
559 driver in-house for something completely different and we know it has
its foibles. In the end we decided programming the 559 in simple mode was
the way to go for us rather than flexible mode. Also, we don't bother with
interrupts and simply poll the device as part of our idle loop.]

Has anyone else seen oddities running the '559 in 100Mbit Full duplex mode ?

FWIW, I tried an 82550 based card and they seem to work exactly as per the
'559 - as you'd expect. For all the folks with short arms and long pockets
out there [like me] I gather 550 based cards are a bit cheaper.

I'm using a current CVS tree with redboot and my test image built from it. I
tried messing around with various network related buffer numbers in ecos.ecc
for redboot before dropping back to the hub but they didn't seem to make any
difference.

Cheers,

John