irq: initialize nr_irqs based on nr_cpu_ids
Impact: Reduce memory usage.
This is the second half of the changes to make the irq_desc_ptrs be
variable sized based on nr_cpu_ids. This is done by adding a new
"max_nr_irqs" macro to irq_vectors.h (and a dummy in irqnr.h) to
return a max NR_IRQS value based on NR_CPUS or nr_cpu_ids.
This necessitated moving the define of MAX_IO_APICS to a separate
file (asm/apicnum.h) so it could be included without the baggage
of the other asm/apicdef.h declarations.
Signed-off-by: Mike Travis <travis@sgi.com>
diff --git a/arch/x86/include/asm/apicdef.h b/arch/x86/include/asm/apicdef.h
index 63134e3..1a6454e 100644
--- a/arch/x86/include/asm/apicdef.h
+++ b/arch/x86/include/asm/apicdef.h
@@ -132,12 +132,8 @@
#define APIC_BASE_MSR 0x800
#define X2APIC_ENABLE (1UL << 10)
-#ifdef CONFIG_X86_32
-# define MAX_IO_APICS 64
-#else
-# define MAX_IO_APICS 128
-# define MAX_LOCAL_APIC 32768
-#endif
+/* get MAX_IO_APICS */
+#include <asm/apicnum.h>
/*
* All x86-64 systems are xAPIC compatible.
diff --git a/arch/x86/include/asm/apicnum.h b/arch/x86/include/asm/apicnum.h
new file mode 100644
index 0000000..82f613c
--- /dev/null
+++ b/arch/x86/include/asm/apicnum.h
@@ -0,0 +1,12 @@
+#ifndef _ASM_X86_APICNUM_H
+#define _ASM_X86_APICNUM_H
+
+/* define MAX_IO_APICS */
+#ifdef CONFIG_X86_32
+# define MAX_IO_APICS 64
+#else
+# define MAX_IO_APICS 128
+# define MAX_LOCAL_APIC 32768
+#endif
+
+#endif /* _ASM_X86_APICNUM_H */
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index f7ff650..602361a 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -105,6 +105,8 @@
#if defined(CONFIG_X86_IO_APIC) && !defined(CONFIG_X86_VOYAGER)
+#include <asm/apicnum.h> /* need MAX_IO_APICS */
+
#ifndef CONFIG_SPARSE_IRQ
# if NR_CPUS < MAX_IO_APICS
# define NR_IRQS (NR_VECTORS + (32 * NR_CPUS))
@@ -112,11 +114,15 @@
# define NR_IRQS (NR_VECTORS + (32 * MAX_IO_APICS))
# endif
#else
-# if (8 * NR_CPUS) > (32 * MAX_IO_APICS)
-# define NR_IRQS (NR_VECTORS + (8 * NR_CPUS))
-# else
-# define NR_IRQS (NR_VECTORS + (32 * MAX_IO_APICS))
-# endif
+
+/* defined as a macro so nr_irqs = max_nr_irqs(nr_cpu_ids) can be used */
+# define max_nr_irqs(nr_cpus) \
+ ((8 * nr_cpus) > (32 * MAX_IO_APICS) ? \
+ (NR_VECTORS + (8 * NR_CPUS)) : \
+ (NR_VECTORS + (32 * MAX_IO_APICS))) \
+
+# define NR_IRQS max_nr_irqs(NR_CPUS)
+
#endif
#elif defined(CONFIG_X86_VOYAGER)
diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 86af92e..de66e4e 100644
--- a/include/linux/irqnr.h
+++ b/include/linux/irqnr.h
@@ -20,11 +20,18 @@
# define for_each_irq_desc_reverse(irq, desc) \
for (irq = nr_irqs - 1; irq >= 0; irq--)
+
#else /* CONFIG_GENERIC_HARDIRQS */
+#include <asm/irq_vectors.h> /* need possible max_nr_irqs() */
+
extern int nr_irqs;
extern struct irq_desc *irq_to_desc(unsigned int irq);
+# ifndef max_nr_irqs
+# define max_nr_irqs(nr_cpus) NR_IRQS
+# endif
+
# define for_each_irq_desc(irq, desc) \
for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs; \
irq++, desc = irq_to_desc(irq)) \
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index d0b8f7e..ebba7a1 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -133,6 +133,9 @@
int legacy_count;
int i;
+ /* initialize nr_irqs based on nr_cpu_ids */
+ nr_irqs = max_nr_irqs(nr_cpu_ids);
+
printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d\n", NR_IRQS, nr_irqs);
desc = irq_desc_legacy;