Re: Message Signalled Interrupt support?

[Mika Penttilä]

I think that  MSI should be made quite explicit. If the device and 
platform both support MSI, then the driver should be able to ask for 
MSI, but kernel must be able to deny it. All devices supporting MSI must 
support also pin based interrupt delivery. As MSI can be costy (one 
interrupt vector per device for instance), it could be that a device has 
to work in pin based mode instead.

--Mika

David S. Miller wrote:

>   From: Matthew Wilcox <[e-mail]>
>   Date: Mon, 12 May 2003 17:53:31 +0100
>
>   On Mon, May 12, 2003 at 12:32:49PM -0400, Jeff Garzik wrote:
>   > Has anybody done any work, or put any thought, into MSI support?
>   
>   Work -- no.  Thought?  A little.  Seems to me that MSIs need to be
>   treated as a third form of interrupts (level/edge/message).
>
>The fact that Alpha already supports them pretty much transparently
>suggests that the thing to do might very well be "nothing" :-)
>
>To be honest, MSIs are very similar to how interrupts work on sparc64,
>in that each device generates a unique interrupt cookie.  The only
>different is the size of this cookie, MSIs are larger than sparc64's.
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