Where do MSI quirks belong? [patch]

[John Polstra]

On 11-Dec-2006 Andre Oppermann wrote:
> IIRC it is not only a chipset problem but also sometimes how a MSI capable
> chipset is wired on the mainboard.

I agree, that is probably the case.  The pci_get_msi_global_quirks
function is intended to be open-ended in the sense that it should do
whatever it needs to do to figure out whether the system as a whole
can support MSI or not.  The function comment mentions checking kenv
strings as an example.  At this point I don't know all of the other
checks that need to be done, but they should all fit into that
function.

> So some probing would have to be done as well.

Actual probing might be risky.  On my Tyan 2721 motherboard, enabling
MSI wedges the system solid, requiring a HW reset to recover.

John