On Wed, Aug 12, 2015 at 02:31:47PM +0100, Marc Zyngier wrote:
> On 11/08/15 10:15, Eric Auger wrote:
> > On 07/09/2015 03:19 PM, Marc Zyngier wrote:
> >> static int gic_irq_set_irqchip_state(struct irq_data *d,
> >> @@ -272,11 +278,15 @@ static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
> >> irqnr = irqstat & GICC_IAR_INT_ID_MASK;
> >>
> >> if (likely(irqnr > 15 && irqnr < 1021)) {
> > shouldn't we have < 1020?
>
> Looks like you have unearthed a very long standing (though not fatal)
> bug - I can trace it back to 2005 and the inclusion of the Realview
> support (see include/asm-arm/arch-realview/entry-macro.S in 8ad68bbf for
> the details).
>
> It may be that the original GIC didn't make number 1020 a special one,
> though the earliest spec I have access to (GICv1) is already making 1020
> a reserved interrupt number. And looking at the pre-existing code
> (arch/arm/common/gic.c), 1020 seems to already be considered an invalid
> number.
>
> CC-ing Catalin, as he was the one who introduced it... ;-) Unless he
> says otherwise, I'll cook a patch for that.
I really have no idea where it came from. The code probably pre-dates
the existence of a GIC architecture spec (the GIC spec used to be part
of the board or CPU TRM).
I don't see any problem with using 1020 here.
--
Catalin
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