Re: kernel panic trying to utilize a da(4)/umass(4) device with ohci(4)

Doug White <dwhite_at_gumbysoft.com> wrote:
> The OHCI driver is largely synced with NetBSD so you might see if they
> have the same bug.

I'll look around for a bootable NetBSD CD.

> This might be the underlying wierdness we were seeing in gtetlow's
> microdrive with transfers over 8k.  The one-page-crossing ohci limitation
> is really annoying.

Is there a way to add a quirk for max 8k transfers or anything?  Even though 
that would be patently lame, I'd like to get some sort of workaround here.  
I don't even know what is supposed to be the problem here -- the fact that 
it's an ohci controller, an ohci+ehci controller, or that it's some specific 
controller issue...

> On Thu, 20 Nov 2003, Brian F. Feldman wrote:
> 
> > Thanks for the patches to try!  They unfortunately didn't fix the crash I
> > have, but I found out why it's occurring.
> >
> > See ohci.c:1389:
> >                 if (std->td.td_cbp != 0)
> >                         len -= le32toh(std->td.td_be) -
> >                                le32toh(std->td.td_cbp) + 1;
> >
> > In one of my transfers (look in my log for the 2560 byte one) that statement
> > actually adds 8192 to len, which is utterly bogus because you can see it
> > only allocates 2560 -- hence when it tries to finish the transfer it
> > memcpy()'s way too much memory and my kernel segfaults.  If I #if 0 this out,
> > I'm left only with "umass0: BBB reset failed, STALLED" messages... which is
> > a lot better than before!  I don't know under what situations that bit of
> > code makes sense, but it definitely needs more reviewing!
> 
> Stalls usually come from the device receiving bad data.  Rather than
> return errors, usb generally just hangs the endpoint.

Hmm :-/  I wonder if anyone could interpret the debugging info enough to 
have an idea what it's disliking for certain.

-- 
Brian Fundakowski Feldman                           \'[ FreeBSD ]''''''''''\
  <> green_at_FreeBSD.org                               \  The Power to Serve! \
 Opinions expressed are my own.                       \,,,,,,,,,,,,,,,,,,,,,,\