Re: Xen regression, Was: [PATCH] x86/irq: Probe for PIC presence before allocating descs for legacy IRQs

[Boris Ostrovsky]

On 04/11/2016 10:08 PM, Stefano Stabellini wrote:
> Hi all,
>
> Unfortunately this patch (now commit
> 8c058b0b9c34d8c8d7912880956543769323e2d8) causes a regression on Xen
> when running on top of QEMU: the number of PIT irqs get set to 0 by
> probe_8259A but actually there are 16.
>
> Any suggestions on how to fix this?
>
> 1) we could revert 8c058b0b9c34d8c8d7912880956543769323e2d8
> 2) we could introduce an 'if (!xen_domain())' in probe_8259A
> 3) suggestions welcome

Stefano, do you have b4ff8389ed14b849354b59ce9b360bdefcdbf99c ?

It was supposed to fix this problem for Xen. However, I just noticed 
that arch/arm64/include/asm/irq.h makes nr_legacy_irqs() return 0 
(unlike arch/arm/include/asm/irq.h). Could that be the problem?


-boris