On Fri, Apr 14, 2000 at 10:28:14AM -0400, Colin Surprenant wrote:

 > I tried "ifconfig ray0 link0" and got this right after doing a ping to
 > the Windows machine:
 > 
 > cpu_Debugger() at cpu_Debugger+0x4
 > panic() at panic+0xe4
 > trap() at trap+0x50c
 > XentUna() at XentUna+0x20
 > --- unaligned access fault (from ipl 1) ---

...

 > fr_makefrip is part of ipf so I disabled ipf and give it a try to see if
 > the problem is ipf-centric and got this again right after doing a ping to
 > the Win machine.
 > 
 > cpu_Debugger() at cpu_Debugger+0x4
 > panic() at panic+0xe4
 > trap() at trap+0x518
 > XentUna() at XentUna+0x20
 > --- unaligned access fault (from ipl 1) ---
 > icmp_input() at icmp_input+0x1b4

 > At this point I didn't investigate further but the problem doesn't seem to
 > be related to ipf.

Problem is pretty obvious :-)  `link0' changes the driver to use a different
encapsulation, which changes the offset of the payload in the packets.  This
difference is causing the IP header to be misaligned, which is All Bad.

The driver needs to be changed to ensure that all payload data is aligned
in whichever encapsulation mode is being used.  This shouldn't really be
that hard, but it may mean that the driver is slightly less memory efficient
in Windows-compatible mode.  The punishment you must endure for running
Windows, I guess[*] :-)

[*] Note that I sometimes must run Windows, too, and use an Alpha as my
wireless gateway, using WebGear cards.  I just haven't had the need to
use the wireless network while Windows is running on the laptop.

-- 
        -- Jason R. Thorpe <thorpej@zembu.com>