[PATCH 1/6] powerpc/kconfig: Move NR_IRQS into "Kernel Options"

[Michael Ellerman]

On Mon, 2015-10-12 at 12:30 +0200, Arnd Bergmann wrote:
> On Monday 12 October 2015 21:00:25 Michael Ellerman wrote:
> > On Thu, 2015-10-08 at 23:30 +0200, Arnd Bergmann wrote:
> > > On Friday 09 October 2015 08:09:12 Michael Ellerman wrote:
> > > > Currently the NR_IRQS option sits at the top level, which is ugly in
> > > > menuconfig. It's not something users will commonly need to worry about
> > > > so move it into "Kernel Options".
> > > 
> > > Is this option actually still meaningful at all, when you select CONFIG_SPARSE_IRQ
> > > unconditionally?
> > 
> > It's still used for #define NR_IRQS, which is still used by the generic irq
> > code and also some drivers.
> 
> Drivers shouldn't use it, and I don't see any driver using it that can be
> enabled on powerpc.
> 
> The question is rather whether you have any devices on powerpc that
> get a hardwired IRQ number from a statically defined platform device
> rather from DT.
> 
> If there are any ISA devices, the driver might try to use an interrupt
> number that is hardcoded in the driver as a number from 0 to 15.
> I guess that could happen on old CHRP or 6xx machines.
> 
> > So we need some value for that, whether it needs to be user defined or if we
> > could just pick a value I'm not sure. x86 seem to just define it based on
> > NR_CPUs and some other factors.
> 
> What happens if you set it to 16?

Yeah, this builds and boots at least on pseries KVM.

diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index e8e3a0a04eb0..35fba282b7f9 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -23,11 +23,8 @@ extern atomic_t ppc_n_lost_interrupts;
 /* This number is used when no interrupt has been assigned */
 #define NO_IRQ                 (0)
 
-/* Total number of virq in the platform */
-#define NR_IRQS                CONFIG_NR_IRQS
-
-/* Same thing, used by the generic IRQ code */
 #define NR_IRQS_LEGACY         NUM_ISA_INTERRUPTS
+#define NR_IRQS                        NR_IRQS_LEGACY
 
 extern irq_hw_number_t virq_to_hw(unsigned int virq);
 

cheers