Re: [PATCH 0/3] msi abstractions and support for altix

Greg KH
2006-01-03T06:07:19Z

On Mon, Jan 02, 2006 at 09:22:49PM -0600, Mark Maule wrote:
> On Thu, Dec 22, 2005 at 01:50:23PM -0700, Matthew Wilcox wrote:
> > On Thu, Dec 22, 2005 at 02:38:24PM -0600, Mark Maule wrote:
> > > Because on ia64 IA64_FIRST_DEVICE_VECTOR and IA64_LAST_DEVICE_VECTOR
> > > (from which MSI FIRST_DEVICE_VECTOR/LAST_DEVICE_VECTOR are derived) are not
> > > constants. The are now global variables (see change to asm-ia64/hw_irq.h)
> > > to allow the platform to override them. Altix uses a reduced range of
> > > vectors for devices, and this change was necessary to make assign_irq_vector()
> > > to work on altix.
> >
> > To be honest, I think this is just adding a third layer of paper over
> > the crack in the wall. The original code assumed x86; the ia64 port
> > added enough emulation to make it look like x86 and now altix fixes a
> > couple of assumptions. I say: bleh.
> >
> > What we actually need is an interface provided by the architecture that
> > allocates a new irq. I have a hankering to implement MSI on PA-RISC but
> > haven't found the time ...
>
> Matt, Greg, et. al:
>
> Did you guys have something in mind for a vector allocation interface? It
> seems to me that assign_irq_vector() more or less does what we want,
> but what is missing is a way for the platform to prime which vectors
> are available to choose from.
>
> One possibly better solution would be to call something in the init_IRQ path
> that would set up the vector pool available to assign_irq_vector().
>
> Any opinions on this? I would maintain that this effort should be done
> independently of this patchset.

Care to write a patch showing how this would work?

And why would this be independant of your other changes?

thanks,

greg k-h