Re: [Xen-devel] [PATCH v4 05/17] xen/arm: ITS: implement hw_irq_controller for LPIs

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Vijay,

On 11/07/2015 16:40, Vijay Kilari wrote:
> > > diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
> > > index e9d5f36..44c2317 100644
> > > --- a/xen/include/asm-arm/gic.h
> > > +++ b/xen/include/asm-arm/gic.h
> > > @@ -20,6 +20,9 @@
> > >
> > >   #define NR_GIC_LOCAL_IRQS  NR_LOCAL_IRQS
> > >   #define NR_GIC_SGI         16
> > > +#define FIRST_GIC_LPI      8192
> > > +#define NR_GIC_LPI         4096
> > > +#define MAX_LPI            (FIRST_GIC_LPI + NR_GIC_LPI)
> > MAX_LPI and NR_GIC_LPI should be obtained from the hardware at init time
> > and put somewhere, like a global nr_lpis perhaps, to be used throughout.
>   This MAX_LPI and NR_GIC_LPI is Xen limitation where in we
> are allocating irq_descriptors statically upto NR_GIC_LPI.
Why? The design doc [1] suggested to allocate dynamically the irq_desc 
array for LPI at boot.
Using a static array will grow up the Xen binary by close to 4096 LPIs * 
60 bytes (rough estimate) = 240 KB.
And this is for any AArch64 platform, no matter that ITS is in used or not.

Regards,

[1] http://xenbits.xen.org/people/ianc/vits/draftG.html#irq-descriptors

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel