Better device probe values

John Baldwin jhb at
Wed Feb 23 13:44:45 PST 2005

On Wednesday 23 February 2005 03:50 pm, Warner Losh wrote:
> > Several typos, but that's minor.  Sounds ok to me.  Note that I think
> > BUS_PROBE_GENERIC might not really be enough though (PCI bridge drivers
> > are actually somewhat tricky, on x86 for PCI-PCI you have ACPI, PCIBIOS,
> > MPTable, and generic for example), but for more tricky cases we can still
> > use numeric values.
> Well, on x86 we have 3 different pci busses, but they aren't in any
> more complicated a heirarchy than 'generic' or something that replaces
> 'generic.'  You won't have PCIBIOS and MPTable fighting for control of
> a system, will you?

Yes, you do.  MPTable is just preferred to PCIBIOS, and ACPI is preferred to 
PCIBIOS.  MPTable probably should be preferred to ACPI though (since 
MPTable's probe is only going to succeed if we are using the MPTable to 
enumerate APICs, in which case we can't trust ACPI's interrupt routing) 
though I might have this one wrong.  All three are preferred over the generic 
bridge driver.  Actually, the ACPI vs. MPTable case is probably a bit more 
muddy than that.  It's probably wrong now.  We shouldn't ever use those two 
together, but I'm not sure how best to do that.  I don't think that is 
currently an issue though because I don't know of any machines that include 
an MP Table and ACPI but don't include an MADT table in ACPI.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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