Re: [RFC] Whitelist chipsets supporting MSI and check Hyper-transport capabilities

[Jeff Garzik <jeff@garzik.org>]

Greg KH wrote:
> On Fri, Jun 16, 2006 at 11:01:46PM -0400, Brice Goglin wrote:
>> Several chipsets are known to not support MSI. Some support MSI but
>> disable it by default. Thus, several drivers implement their own way to
>> detect whether MSI works.
>>
>> We introduce whitelisting of chipsets that are known to support MSI and
>> keep the existing backlisting to disable MSI for other chipsets. When it
>> is unknown whether the root chipset support MSI or not, we disable MSI
>> by default except if pci=forcemsi was passed.
>>
>> Whitelisting is done by setting a new PCI_BUS_FLAGS_MSI in the chipset
>> subordinate bus. pci_enable_msi() thus starts by checking whether the
>> root chipset of the device has the MSI or NOMSI flag set.
> 
> Whitelisting looks all well and good today, and maybe for the rest of
> the year.  But what about 3 years from now when everyone has shaken all
> of the MSI bugs out of their chipsets finally?  Do you really want to
> add a new quirk for _every_ new chipset that comes out?  I don't think
> that it is managable over the long run.
> 
> I do like your checks to see if MSI is able to be enabled or not, and
> maybe we can just invert them to mark those chips that do not support
> MSI today?

My gut feeling is:

blacklist -> any Intel machines which fail (most work)
blacklist -> any PCI Express which fails (most should work)
whitelist -> any other situation which works

Regards,

	Jeff