Re: FTP stalls on tl0 on Challenge S

["Stephen M. Rumble" <rumble%cs.stanford.edu@localhost>]

On Mar 26, 2010, at 7:43 PM, Stephen M. Rumble wrote:

> On Mar 26, 2010, at 3:21 PM, George Harvey wrote:
> 
>> Good call, the bad checksum count does increment. Wireshark says the IP
>> and TCP checksums are good so that tends to confirm the problem's in
>> the SGI.
> 
> Hi George,
> 
> Sounds like we may be messing up the receive DMA. Could you try the attached 
> patch (against src/sys/dev/pci/if_tl.c)? I recall correctly, I eventually 
> discovered that this nic's pci<->gio bus bridge can't DMA across page 
> boundaries. I fixed the TX side, but for some reason neglected RX. I don't 
> recall if I just forgot to handle the RX case and it worked well enough, or 
> if I believed it wasn't necessary for some reason.

Hrm. Actually, just the RX descriptor ring boundary restriction was missed, not 
the RX buffers themselves. It might still be worth trying the patch if it's 
quick to do, but it doesn't look like the glaring omission I thought it was.

Steve