Re: [PATCH] qemu-kvm: fix no gsi routing warning

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Sep 21, 2009 at 05:56:13PM +0300, Avi Kivity wrote:
> On 09/21/2009 05:51 PM, Michael S. Tsirkin wrote:
>> When running on host kernel which does not let the guest manupulate the
>> gsi routing, and user requested MSI-X to be enabled, we get the
>> following warnings:
>> kvm_msix_add: kvm_get_irq_route_gsi failed: No space left on device
>> kvm_msix_update: kvm_update_routing_entry failed: Invalid argument
>>
>> What really happens is that we report a failure to allocate
>> a vector to the guest, it will retry and finally disable MSI.
>>
>> Make this clearer by checking for gsi capability and warning about
>> the error in a readable form.
>>
>>    
>
> Can we disable msix

What we do effectively disables msix.

> (or, abort qemu at startup and request that the user  
> disable msix) if the kernel doesn't provide required features?
>  It's  
> better than a runtime error.

Note it's a warning, not an error.

We have a similar failure mode when we run out of gsi entries, and that
can not be checked upfront.  I prefer having it fail in the same way, so
that this failure path in guest drivers is excercised and tested.

> -- 
> error compiling committee.c: too many arguments to function