On Tue, Oct 13, 2009 at 11:44 PM, Michael Ellerman <mich...@ellerman.id.au> wrote: > The irq_desc array consumes quite a lot of space, and for systems > that don't need or can't have 512 irqs it's just wasted space. > > The first 16 are reserved for ISA, so the minimum of 32 is really > 16 - and no one has asked for more than 512 so leave that as the > maximum.
Does it really make sense to have this as a user twiddlable value? Especially when many users just don't have the background to know what an appropriate value is here and will get it wrong? I believe your sparse IRQ patch has a bigger impact anyway on systems where memory is tight. g. > > Signed-off-by: Michael Ellerman <mich...@ellerman.id.au> > --- > arch/powerpc/Kconfig | 10 ++++++++++ > arch/powerpc/include/asm/irq.h | 4 ++-- > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 10a0a54..2230e75 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -56,6 +56,16 @@ config IRQ_PER_CPU > bool > default y > > +config NR_IRQS > + int "Number of virtual interrupt numbers" > + range 32 512 > + default "512" > + help > + This defines the number of virtual interrupt numbers the kernel > + can manage. Virtual interrupt numbers are what you see in > + /proc/interrupts. If you configure your system to have too few, > + drivers will fail to load or worse - handle with care. > + > config STACKTRACE_SUPPORT > bool > default y > diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h > index bbcd1aa..b83fcc8 100644 > --- a/arch/powerpc/include/asm/irq.h > +++ b/arch/powerpc/include/asm/irq.h > @@ -34,8 +34,8 @@ extern atomic_t ppc_n_lost_interrupts; > */ > #define NO_IRQ_IGNORE ((unsigned int)-1) > > -/* Total number of virq in the platform (make it a CONFIG_* option ? */ > -#define NR_IRQS 512 > +/* Total number of virq in the platform */ > +#define NR_IRQS CONFIG_NR_IRQS > > /* Number of irqs reserved for the legacy controller */ > #define NUM_ISA_INTERRUPTS 16 > -- > 1.6.2.1 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev > -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
