> ----------------->
> Subject: x83: i386 IOAPIC: de-fang IRQ compression
> From:
ebiederm@xmission.com (Eric W. Biederman)
>
> Due to hardware and software implementation limits the i386 kernel
> can only use 224 or so different IRQs at one time. However except
> for actually having the irqs delivered there are no limits except
> the arbitrary number NR_IRQS on how many irqs we can talk about
> and deal with.
>
> Frequently not all io_apics inputs are connected to interrupt traces
> going to real devices, and since even when they are devices don't
> always use all of interrupt traces routed to them. So it makes
> sense to be able to talk about many more irq sources then we can
> actually use.
>
> So this patch consolidates NR_IRQS and NR_IRQ_VECTORS into just
> NR_IRQS and raises NR_IRQS where appropriate above the number of
> irqs we can use at one time.
>
> Allowing the kernel to work on big machines without complicated
> and error prone irq remapping logic.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/kernel/acpi/boot.c | 4 ++--
> arch/x86/kernel/io_apic_32.c | 4 ++--
> include/asm-x86/mach-default/irq_vectors_limits.h | 8 +++-----
> include/asm-x86/mach-generic/irq_vectors_limits.h | 3 +--
> include/asm-x86/mach-summit/irq_vectors_limits.h | 3 +--
> include/asm-x86/mach-visws/irq_vectors.h | 1 -
> include/asm-x86/mach-voyager/irq_vectors.h | 1 -
> 7 files changed, 9 insertions(+), 15 deletions(-)
>
> Index: linux-x86.q/arch/x86/kernel/acpi/boot.c
> ===================================================================
> --- linux-x86.q.orig/arch/x86/kernel/acpi/boot.c
> +++ linux-x86.q/arch/x86/kernel/acpi/boot.c
> @@ -855,7 +855,7 @@ static int __init acpi_parse_madt_ioapic
>
> count =
> acpi_table_parse_madt(ACPI_MADT_TYPE_INTERRUPT_OVERRIDE,
> acpi_parse_int_src_ovr,
> - NR_IRQ_VECTORS);
> + NR_IRQS);
> if (count < 0) {
> printk(KERN_ERR PREFIX
> "Error parsing interrupt source overrides entry\n");
> @@ -875,7 +875,7 @@ static int __init acpi_parse_madt_ioapic
>
> count =
> acpi_table_parse_madt(ACPI_MADT_TYPE_NMI_SOURCE, acpi_parse_nmi_src,
> - NR_IRQ_VECTORS);
> + NR_IRQS);
> if (count < 0) {
> printk(KERN_ERR PREFIX "Error parsing NMI SRC entry\n");
> /* TBD: Cleanup to allow fallback to MPS */
> Index: linux-x86.q/arch/x86/kernel/io_apic_32.c
> ===================================================================
> --- linux-x86.q.orig/arch/x86/kernel/io_apic_32.c
> +++ linux-x86.q/arch/x86/kernel/io_apic_32.c
> @@ -1191,14 +1191,14 @@ static inline int IO_APIC_irq_trigger(in
> }
>
> /* irq_vectors is indexed by the sum of all RTEs in all I/O APICs. */
> -static u8 irq_vector[NR_IRQ_VECTORS] __read_mostly = { FIRST_DEVICE_VECTOR , 0
> };
> +static u8 irq_vector[NR_IRQS] __read_mostly = { FIRST_DEVICE_VECTOR , 0 };
>
> static int __assign_irq_vector(int irq)
> {
> static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0;
> int vector, offset;
>
> - BUG_ON((unsigned)irq >= NR_IRQ_VECTORS);
> + BUG_ON((unsigned)irq >= NR_IRQS);
>
> if (irq_vector[irq] > 0)
> return irq_vector[irq];
> Index: linux-x86.q/include/asm-x86/mach-default/irq_vectors_limits.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/mach-default/irq_vectors_limits.h
> +++ linux-x86.q/include/asm-x86/mach-default/irq_vectors_limits.h
> @@ -2,15 +2,13 @@
> #define _ASM_IRQ_VECTORS_LIMITS_H
>
> #if defined(CONFIG_X86_IO_APIC) || defined(CONFIG_PARAVIRT)
> -#define NR_IRQS 224
> -# if (224 >= 32 * NR_CPUS)
> -# define NR_IRQ_VECTORS NR_IRQS
> +# if (200 >= 32 * NR_CPUS)
> +# define NR_IRQS 200
> # else
> -# define NR_IRQ_VECTORS (32 * NR_CPUS)
> +# define NR_IRQS (32 * NR_CPUS)
> # endif
> #else
> #define NR_IRQS 16
> -#define NR_IRQ_VECTORS NR_IRQS
> #endif
>
> #endif /* _ASM_IRQ_VECTORS_LIMITS_H */
> Index: linux-x86.q/include/asm-x86/mach-generic/irq_vectors_limits.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/mach-generic/irq_vectors_limits.h
> +++ linux-x86.q/include/asm-x86/mach-generic/irq_vectors_limits.h
> @@ -8,7 +8,6 @@
> * This value should be the same in both the generic and summit subarches.
> * Change one, change 'em both.
> */
> -#define NR_IRQS 224
> -#define NR_IRQ_VECTORS 1024
> +#define NR_IRQS 1024
>
> #endif /* _ASM_IRQ_VECTORS_LIMITS_H */
> Index: linux-x86.q/include/asm-x86/mach-summit/irq_vectors_limits.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/mach-summit/irq_vectors_limits.h
> +++ linux-x86.q/include/asm-x86/mach-summit/irq_vectors_limits.h
> @@ -8,7 +8,6 @@
> * This value should be the same in both the generic and summit subarches.
> * Change one, change 'em both.
> */
> -#define NR_IRQS 224
> -#define NR_IRQ_VECTORS 1024
> +#define NR_IRQS 1024
>
> #endif /* _ASM_IRQ_VECTORS_LIMITS_H */
> Index: linux-x86.q/include/asm-x86/mach-visws/irq_vectors.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/mach-visws/irq_vectors.h
> +++ linux-x86.q/include/asm-x86/mach-visws/irq_vectors.h
> @@ -51,7 +51,6 @@
> */
> #define NR_VECTORS 256
> #define NR_IRQS 224
> -#define NR_IRQ_VECTORS NR_IRQS
>
> #define FPU_IRQ 13
>
> Index: linux-x86.q/include/asm-x86/mach-voyager/irq_vectors.h
> ===================================================================
> --- linux-x86.q.orig/include/asm-x86/mach-voyager/irq_vectors.h
> +++ linux-x86.q/include/asm-x86/mach-voyager/irq_vectors.h
> @@ -57,7 +57,6 @@
>
> #define NR_VECTORS 256
> #define NR_IRQS 224
> -#define NR_IRQ_VECTORS NR_IRQS
>
> #define FPU_IRQ 13
>
