Re: [Xen-devel] [PATCH 05/11] xen/arm: vpl011: Initialize nr_spis in vgic_init in Xen to atleast 1

[Bhupinder Thakur <bhupinder.thakur@xxxxxxxxxx>]

On 16 March 2017 at 13:54, Julien Grall <julien.grall@xxxxxxx> wrote:
>>
>> The other option is to reserve a SPI for pl011 at compile time and use
>> that value. Let me know.
>
>
> Whilst I am ok to have the pl011 SPI number hardcoded, I don't like the
> approach taken in this patch because the toolstack is in charge of the guest
> layout (interrupt, memory...) and not the hypervisor.
>
> The values are hardcoded today because we decided to do a fix layout for
> simplicity. It is likely to be changed in the future.
>
> The toolstack knows how much memory the user requested, the list of devices
> available... So it is the goal of the toolstack to bump the number of SPIs
> before creating the domain if a PL011 will be exposed.
>
> Also, the interaction between the pl011 and the parameter "irqs" in the
> domain configuration file will need to be documented. By that I mean
> explaining from which number the SPIs will be allocated when choosing a
> pl011 enabling.
>
> Note the probably want to allow the user to choose the pl011 IRQ and MMIO
> region. If he doesn't provide any, we would use the default value.
>
> Cheers,

We can follow the convention that when pl011 is enabled then the last
irq in the "irqs" list will be used as the pl011 irq. I believe that
the irqs mentioned in the "irqs" list will be reserved by the
hypervisor when the domain is created and we need not allocate a SPI
separately as we are doing currently.

One more parameter will be added "pl011" in the configuration to
indicate whether pl011 is enabled or not. By default it will disabled.

With this change, we can remove the pl011 virq HVM parameter.

Regards,
Bhupinder

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