From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: pvops-2.6.32 - Interrupt routing problem
Date: Sun, 21 Mar 2010 23:24:30 -0700
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To: Bastian Blank <waldi@debian.org>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Keir Fraser <keir.fraser@eu.citrix.com>, "Zhang,
	Xiantao" <xiantao.zhang@intel.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
List-Id: xen-devel@lists.xenproject.org

On 03/21/2010 02:47 PM, Bastian Blank wrote:
> On Fri, Mar 19, 2010 at 01:13:41PM +0100, Bastian Blank wrote:
>    
>> The real fix could be:
>> - Allow the hypervisor to lock interrupts it uses. Zero would be in it by
>>    default. The interrupt for the used serial interface would be added.
>>    All other pins are free to be programmed by the kernel once.
>> - Don't do register_gsi calls from the initial setup in the kernel if no
>>    ACPI override is present, only setup the rest.
>>      
> Okay, I think I found another problem. Currently the setup looks like
> this:
> - PHYSDEVOP_setup_gsi: set trigger and polarity, unmask pin
> - PHYSDEVOP_map_pirq: map to pirq, set irq handler to guest
>
> If an interrupt fires between this two calles, what happens?
>    

Doesn't sound like a good thing to be doing.  The unmask should probably 
be deferred until everything has been set up to receive an interrupt.

> Usually I would do the setup the other way around. This would also make
> it possible to use the irq table to allow the kernel to only set IO-APIC
> pins mapped to already properly registered interrupts.
>    

Sounds reasonable.

     J