Subject: RE: DMA troubles
To: None <tech-kern@netbsd.org>
From: Filka Michal <michal.filka@strom.cz>
List: tech-kern
Date: 04/26/2006 10:08:33
> > Hi all,
> > I have a problem (possibly) with DMA. I can allocate a DMA memory in
my
> > driver and work with it without any troubles. However, If I unload
> > driver (it is a LKM) and try to load it again, kernel crashes during
DMA
> > memory allocation. I did a DMA deinitialization when unloading
driver
>=20
> How does it crash ?

... it breaks into kernel debugger (Page fault trap) during the call of
"bus_dmamem_alloc". I made a simple skeleton of my driver which is only
loaded and unloaded and it still fails in second attempt for loading it.
First attempt loads/unloads without any troubles. All this happens even
if I do only "..._alloc" and "..._free" with no other operations on
DMAed memory.

Any ideas are very welcome.

Michal Filka