Re: Multiple MSI

[Matthew Wilcox <matthew@wil.cx>]

On Thu, Jul 03, 2008 at 02:41:59PM +1000, Benjamin Herrenschmidt wrote:
> Ok, so I lift my objection there in the sense that allocating a linear
> array of virtual numbers shouldn't be a problem (somebody remind me to
> make NR_IRQS a config option one of these days on ppc, or help with just
> getting rid of irq_desc array alltogether :-)

;-)

> However, do you want to still keep the fact that they are power-of-2
> aligned up to the API or can I just do a linear block allocation for
> virtual number sand require drivers to do the appropriate
> addition/subtraction to get the N'th one ? I will need to allocate
> appropriately aligned HW numbers but that's done via different
> mechanisms (and in some case not even under full linux control, ie,
> hypervisor/firmware does it on pSeries).

Similar situation on x86-64, so I already thought about it ;-)  I think
the IRQ numbers should be contiguous, but not necessarily aligned.
They are, after all, virtual.

> > By the way, would people be interested in changing the MSI-X API to get
> > rid of the msix_entry array?  If allocating consecutive IRQs isn't a
> > problem, then we could switch the MSI-X code to use consecutive IRQs.
> 
> It would make a lot of code simpler...

It certainly would!

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
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