Re: [PATCH 1/1] pci: Block config access during BIST (resend)

Benjamin Herrenschmidt
2005-02-01T23:01:17Z

On Tue, 2005-02-01 at 17:47 +0000, Matthew Wilcox wrote:
> On Tue, Feb 01, 2005 at 11:35:05AM -0600, Brian King wrote:
> > >If we've done a write to config space while the adapter was blocked,
> > >shouldn't we replay those accesses at this point?
> >
> > I did not think that was necessary.
>
> We have to do *something*. We can't just throw away writes.

I think we can in fact. Again, nobody outside of the driver has
legitimacy to write to the config space of a device, especially if the
device is "unreachable" (either doing a BIST or power managed).

> I see a few options:
>
> - Log all pending writes to config space and replay the log when the
> device is unblocked.
> - Fail writes to config space while the device is blocked.

I agree that returning an error in this case would be a good idea.

> - Write to the saved config space and then blat the saved config space
> back to the device upon unblocking.
>
> Any other ideas?
>
> BTW, you know things like XFree86 go completely around the kernel's PCI
> accessors and poke at config space directly?

Not anymore afaik. They use /proc/bus/pci

Ben.