MSI support on Linux PCI implementation for Ocotea

[Shawn Jin]

> Hi ! What is Ocotea ! :)

Did I spell it wrong?? I don't believe Ben doesn't know Ocotea.
Hmmm...Ocotea again? Let me check if I really spelled it wrong. Hey,
it's really Ocotea. ;)

Of course, there is no such MSI support specific for Ocotea.

> > 1. Obviously MSI is supported in Linux 2.6.x, maybe even in 2.4.x. But
> > MSI implementation seems to support only IOxAPIC on x86 or IA64
> > architectures, though the implemenation is in generic drivers/pci
> > tree.
>
> Exact. And it's also a pile of crap.

;) I'm not in a position where I can either agree or disagree with
you. :D But may I ask if ppc platform can make use of this crap in our
PCI express testing? That is, are the functionalities of this crap
working?

> pci host bridges are initialized early, generally in setup_arch() and
> the PCI bus is probed later. You can see the code in
> arch/powerpc/kernel/pci_{32,64}.c
>
> Now, regarding MSI, as you have noticed, the situation isn't great. I'm
> currently in the middle of reworking our interrupt management (and
> interrupt numbers allocation layer) and Michael Ellermann is looking at
> the MSI issue in parallel.
>
> We don't have a solution yet but are working on it.

It's good to know the development status. What's the relationship
between generic pci driver layer in drivers/pci and architecture
specific implementation? One thing I notice is that architectures
provide pcibios_init() and do resource allocation while the generic
driver provides PCI generic functions such as pci_scan_device().

Thanks,
-Shawn.