Re: Can anyone please fix iwn ?

[David Young <dyoung%pobox.com@localhost>]

On Mon, Sep 08, 2008 at 09:49:53PM +0200, Marcin M. Jessa wrote:
> Danny Cautaert wrote:
> >On 2008-09-06, Marcin M. Jessa <lists%yazzy.org@localhost> wrote:
> >  
> >>I discussed this with someone on #NetBSD on freenode who is using the 
> >>same driver and his NetBSD crashed immediately right after he started 
> >>downloading a torrent file (have you tried it yourself?).
> >>This also never happens on kernels without iwn when I instead use a wired 
> >>nic.
> >>    
> >
> >That was me. Indeed, generally the driver works well for me, but
> >starting a torrent immediatly locked up the machine. 
> >  
> Can anyone take look at this issue please?
> This bug is randomly taking down my system making it virtually 
> impossible to work on.
> The easiest and simplest way to trigger/reproduce this is to download a 
> torrent
> but this happens to me very often when I simply browse the web.

There may be a buffer overrun bug in the driver or NIC.  How big are
the rx buffers that iwn allocates?  An 802.11n NIC may expect for each
rx buffer to be as large as 8kB.  If iwn reserves only 2kB for an rx
buffer, the h/w may merrily overrun the buffer.  One way to test for
overrun is to reserve some bytes after the rx buffer for the driver,
write a pattern (0xdeadbeef) to the reserved bytes, and check that the
pattern is intact after you receive each frame.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933 ext 24