Re: [PATCH] i386 IOAPIC: de-fang IRQ compression

[Ingo Molnar <mingo@elte.hu>]

* Eric W. Biederman <ebiederm@xmission.com> wrote:

> Attached below is my patch from last time I was looking at this 
> problem, it doesn't quite apply but it is gives a good idea of where I 
> think we should go.

merged it up to x86.git - see below. Alan, have no tried to build, let 
alone boot it. Does it look good to you?

	Ingo

----------------->
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
 
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