Change in PCI behaviour

[Benjamin Herrenschmidt]

On Mon, 2010-11-22 at 03:01 -0700, Gary Thomas wrote:
> I have a bit more information on this.  I'm pretty sure that the failures
> are only happening in my SCSI (SATA actually) code.  My board (8347ea) has
> a PCI bus with a SIL SATA controller.  This combo works perfectly in 2.6.28.
> In 2.6.32, it will run for a while (possibly quite a while), then timeout
> trying to do a large block write - typically 256 blocks.  Once this timeout
> happens, the SIL controller is stuck and accesses to it will eventually
> cause the whole system to hang (as above).
> 
> Was there any major change in how PCI or DMA was handled between 2.6.28
> and 2.6.32?  Given the ephemeral nature of these failures (multiple runs
> all eventually fail, but never the same twice), my only hope of fixing it
> will be to have some ideas what might have changed.

Maybe the changes you did to the PCI outbound windows are now breaking
DMA ? Make sure the outbound and inbound don't overlap for example and
that all RAM is reachable for inbound.

Cheers,
Ben.