start of some pci cleanups

[Andy Ritger]

On Wed, 20 Jul 2005, Benjamin Herrenschmidt wrote:

> On Tue, 2005-07-19 at 08:57 -0700, Andy Ritger wrote:
> > When modifying existing structures and functions, please be conscious
> > of binary compatibility.
> 
> In that case, there is no real choice I'm afraid, that stuff need to be
> cleaned up...
> 
> It might be possible to get a first patch in that only removes the use
> of the direct IO port access for PCI config on x86 and uses /proc
> instead as it does on other architectures. That would be a big step
> forward already without breaking backward compatibility. But we need to
> get the PCI & VGA IO stuff cleaned up as well and that will
> unfortunately cause some breakage.

Understood.  If interfaces need to change, then by all means please
do so.  However, in many cases, there are alternate solutions like
adding a separate entry point, rather than changing the arguments
to an existing entry point.  Similarly, a new field like 'domain'
could be added at the end of pciVideoRec rather than inside PciBusId.

If the ABI needs to be changed, then have good reason and do it
consciously, and please give vendors a way to know which version
of the ABI should be used, so users know which build of the driver
to install.

I know there have been some plans in the works for other ABI changes,
like Kevin Martin's DMX work to eliminate the MAXSCREENS compile
time constant.  It might be good to time these things such that
they can all be encompassed in a single rev of the ABI.

Thanks,
- Andy