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Re: [Xen-devel] [PATCH 3/5] setup_irq/request_irq/free_irq fixups

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 3/5] setup_irq/request_irq/free_irq fixups
From: Espen Skoglund <espen.skoglund@xxxxxxxxxxxxx>
Date: Fri, 6 Feb 2009 11:44:19 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Espen Skoglund <espen.skoglund@xxxxxxxxxxxxx>
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[Keir Fraser]
> On 06/02/2009 11:24, "Espen Skoglund" <espen.skoglund@xxxxxxxxxxxxx> wrote:
>>>> Make setup_irq/request_irq/free_irq take vector param instead of
>>>> irq param
>> 
>>> Do you really think that's an improvement?
>> 
>> Yes.  Some interrupts, e.g., for handling IOMMU faults, do not need
>> to be associated with a pirq.  They just need to have a vector
>> allocated to them.  The way this used to work, the caller would
>> have to invent a IRQ to go with the vector (typically irq :=
>> vector) befor calling the function.

> My reading of the patch was that you simply pushed irq_to_vector()
> out into every caller. I therefore just took the ->shutdown() fix
> for free_irq() and dropped the rest. I checked in the rest of your
> patches.

Hmmm... yeah.  The patch probably didn't make this very clear since
some of the callers just invoke the function with the vector as the
parameter (and hence these callers were not included in the patch).

Anyhow, if you drop the vector parameter the IOMMU related interrupts
will most certainly not work since we no longer update the
irq_to_vector() array with those entries.

        eSk



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