Re: Strange PCI bug

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

On Tue, Jul 31, 2018 at 06:11:32PM +0200, Maxime Villard wrote:
> It is really strange. The fact that we receive exception 0x10 seems to
> indicate that there is a problem somewhere related to the pin/irq
> initialization, but I don't really see how the delay could fix that. Or
> maybe the printfs do something more than just adding delay, I don't
> really know.
> 
> Does that ring a bell to someone? Running out of ideas... Phew, I liked
> these machines...

Supposing it is actually a PCI exception:

Maybe the delay gives the target of the `outl` enough time to finish
some initialization.  Maybe the target doesn't respond to PCI
I/O-space writes until the initialization has finished, and the write
is retried until some retry limit is exceeded.

It's also possible that the PCI I/O-space access generated by the `outl`
is flushing a posted PCI memory-space access, and it's the memory-space
access that causes a PCI exception.

Can you look at the PCI error state on the bridges and devices in the
system?  I don't remember if `ddb` will show that, but it may not be
hard to add.  The error state may lead you quickly to the precise device
that's generating the exception.
 
Dave

-- 
David Young
dyoung%pobox.com@localhost    Urbana, IL    (217) 721-9981