Messages in this thread | | | From | Segher Boessenkool <> | Subject | Re: [PATCH 2/2] Initial generic hypertransport interrupt support. | Date | Tue, 11 Jul 2006 09:29:29 +0200 |
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> As for supporting multiple irqs in plain MSI mode, I don't think > we want to do that. The problem is that multiple interrupts > in msi mode cannot be individually routed.
On some(/many/most) platforms that isn't a problem. Platforms for which it is can just refuse to allocate more than one MSI at once.
> I think we really want > to encourage vendors who are building cards with multiple MSI irqs > to use MSI-X. MSI-X has a lot fewer ugly special cases and all > architectures can individually route the irqs.
We still should support whatever hardware already exists, if possible.
> If there are interesting cards that support just MSI mode and really > need more than one irq I would be happy to reconsider that decision > but my impression was that plain MSI was basically not quite flexible > enough to really be interesting, and supporting just one MSI irq was > ok but any more would lead to all kinds of strange special cases.
Individual drivers can deal with those special cases if they are device- specific; and the platform can just refuse to do more than one MSI if something platform-specific would prevent correct operation.
It would be nice to have the MSI and MSI-X interfaces have the same calling convention; in fact, they can probably be folded into one.
Segher
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