Re: [Xen-devel] [PATCH v2] xen/events: Always allocate legacy interrupts on PV guests

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 18 Nov 2015, Boris Ostrovsky wrote:
> After commit 8c058b0b9c34 ("x86/irq: Probe for PIC presence before
> allocating descs for legacy IRQs") early_irq_init() will no longer
> preallocate descriptors for legacy interrupts if PIC does not
> exist, which is the case for Xen PV guests.
> 
> Therefore we may need to allocate those descriptors ourselves.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

You need to do this for arm64 too.

FYI you can download arm64 cross-compilers from
https://releases.linaro.org/14.04/components/toolchain/binaries/
then you can use them by exporting ARCH=arm64 and
CROSS_COMPILE=/path/to/gcc-linaro-aarch64-linux-gnu-version/bin/aarch64-linux-gnu-


> v2: Use nr_legacy_irqs() instead of NR_IRQS_LEGACY (needs definition for ARM)
> 
>  arch/arm/include/asm/irq.h       | 4 ++++
>  drivers/xen/events/events_base.c | 5 +++--
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
> index be1d07d..b864f60 100644
> --- a/arch/arm/include/asm/irq.h
> +++ b/arch/arm/include/asm/irq.h
> @@ -2,6 +2,10 @@
>  #define __ASM_ARM_IRQ_H
>  
>  #define NR_IRQS_LEGACY       16
> +static inline int nr_legacy_irqs(void)
> +{
> +     return NR_IRQS_LEGACY;
> +}
>  
>  #ifndef CONFIG_SPARSE_IRQ
>  #include <mach/irqs.h>
> diff --git a/drivers/xen/events/events_base.c 
> b/drivers/xen/events/events_base.c
> index 849500e..524c221 100644
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -39,6 +39,7 @@
>  #include <asm/irq.h>
>  #include <asm/idle.h>
>  #include <asm/io_apic.h>
> +#include <asm/i8259.h>
>  #include <asm/xen/pci.h>
>  #endif
>  #include <asm/sync_bitops.h>
> @@ -420,7 +421,7 @@ static int __must_check xen_allocate_irq_gsi(unsigned gsi)
>               return xen_allocate_irq_dynamic();
>  
>       /* Legacy IRQ descriptors are already allocated by the arch. */
> -     if (gsi < NR_IRQS_LEGACY)
> +     if (gsi < nr_legacy_irqs())
>               irq = gsi;
>       else
>               irq = irq_alloc_desc_at(gsi, -1);
> @@ -446,7 +447,7 @@ static void xen_free_irq(unsigned irq)
>       kfree(info);
>  
>       /* Legacy IRQ descriptors are managed by the arch. */
> -     if (irq < NR_IRQS_LEGACY)
> +     if (irq < nr_legacy_irqs())
>               return;
>  
>       irq_free_desc(irq);
> -- 
> 2.1.0
> 

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