From 326487754de59fbb249299c9da5427b780e08949 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Sat, 31 Jan 2009 02:56:44 +0100
Subject: [PATCH] --- yaml --- r: 136675 b: refs/heads/master c:
 009eb3fe146aa6f1951f3c5235851bb8d1330dfb h: refs/heads/master i:   136673:
 57c34e2d8d198d9c7f4eaa29d986bf2c1efd6053   136671:
 74e4fd166b7cd4c464f26f56a1ea1d455c8cf60d v: v3

---
 [refs]                                   |  2 +-
 trunk/arch/x86/include/asm/irq_vectors.h | 32 +++++++++++++++++-------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/[refs] b/[refs]
index 79e2cfd889ae..c05a7f3327d1 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c379698fdac7cb65c96dec549850ce606dd6ceba
+refs/heads/master: 009eb3fe146aa6f1951f3c5235851bb8d1330dfb
diff --git a/trunk/arch/x86/include/asm/irq_vectors.h b/trunk/arch/x86/include/asm/irq_vectors.h
index ec87910025d5..41e2450e13bd 100644
--- a/trunk/arch/x86/include/asm/irq_vectors.h
+++ b/trunk/arch/x86/include/asm/irq_vectors.h
@@ -126,23 +126,37 @@
 #define LAST_VM86_IRQ			  15
 #define invalid_vm86_irq(irq)		((irq) < 3 || (irq) > 15)
 
+/*
+ * Size the maximum number of interrupts.
+ *
+ * If the irq_desc[] array has a sparse layout, we can size things
+ * generously - it scales up linearly with the maximum number of CPUs,
+ * and the maximum number of IO-APICs, whichever is higher.
+ *
+ * In other cases we size more conservatively, to not create too large
+ * static arrays.
+ */
+
 #define NR_IRQS_LEGACY			  16
 
+#define CPU_VECTOR_LIMIT		(  8 * NR_CPUS      )
+#define IO_APIC_VECTOR_LIMIT		( 32 * MAX_IO_APICS )
+
 #ifdef CONFIG_X86_IO_APIC
-# ifndef CONFIG_SPARSE_IRQ
+# ifdef CONFIG_SPARSE_IRQ
+#  define NR_IRQS					\
+	(CPU_VECTOR_LIMIT > IO_APIC_VECTOR_LIMIT ?	\
+		(NR_VECTORS + CPU_VECTOR_LIMIT)  :	\
+		(NR_VECTORS + IO_APIC_VECTOR_LIMIT))
+# else
 #  if NR_CPUS < MAX_IO_APICS
-#   define NR_IRQS 			(NR_VECTORS + (32 * NR_CPUS))
+#   define NR_IRQS 			(NR_VECTORS + 4*CPU_VECTOR_LIMIT)
 #  else
-#   define NR_IRQS			(NR_VECTORS + (32 * MAX_IO_APICS))
+#   define NR_IRQS			(NR_VECTORS + IO_APIC_VECTOR_LIMIT)
 #  endif
-# else
-#  define NR_IRQS					\
-	((8 * NR_CPUS) > (32 * MAX_IO_APICS) ?		\
-		(NR_VECTORS + (8 * NR_CPUS)) :		\
-		(NR_VECTORS + (32 * MAX_IO_APICS)))
 # endif
 #else /* !CONFIG_X86_IO_APIC: */
-# define NR_IRQS			16
+# define NR_IRQS			NR_IRQS_LEGACY
 #endif
 
 #endif /* _ASM_X86_IRQ_VECTORS_H */