cvs commit: src/sys/dev/em if_em.c

[M. Warner Losh]

In message: <43B1D120.9080604 at root.org>
            Nate Lawson <nate at root.org> writes:
: Scott Long wrote:
: > Nate Lawson wrote:
: >> This probably means that the PCI memory space isn't fully initialized 
: >> but an interrupt has been triggered.  If you then go and try to poke 
: >> the hardware, then you can hang the system.
: >>
: > 
: > I can believe your first statement, but not your second.  Hanging the
: > system on an aborted memory read cycle (as opposed to just throwing a
: > #SERR) would indicate a highly highly broken chipset.  In any case, if
: > we ever implement PCI hotplug then we'll have to deal with the effects
: > of aborted PCI transfers anyways.
: > 
: > Scott
: 
: It's not the PCI write that hangs the system, it's the behavior of the 
: device written to.  It may never release the interrupt.  Using an NMI to 
: debug would be good.

Chances are there's a suprious interrupt (from the device's point of
view) that gets into emintr.  Since the em driver doesn't mark itself
as 'suspended' and use that to short-circuit the ISR, we hit this
problem.  I think that this is most likely the problem...

Warner