[PATCH 36/38] x86: according to nr_cpu_ids to decide if need to leave logical flat

[Yinghai Lu <yinghai@kernel.org>]

should use nr_cpu_ids instead of num_processor, in case we have hotplug cpus.

if current only have 8 cpus is up, but if we will have more cpus that
will be hot added later, we should use physical flat at first.

nr_cpu_ids is the total cpus that could be supported.

-v2: per linus, chenage default_setup_apic_routing to _init, and call it for uni_processor

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 arch/x86/kernel/apic/apic.c     |    2 --
 arch/x86/kernel/apic/probe_32.c |   20 ++++++++++++++++++--
 arch/x86/kernel/apic/probe_64.c |    6 +++++-
 arch/x86/kernel/smpboot.c       |    2 --
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 3987e44..3f2bfb1 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1641,9 +1641,7 @@ int __init APIC_init_uniprocessor(void)
 #endif
 
 	enable_IR_x2apic();
-#ifdef CONFIG_X86_64
 	default_setup_apic_routing();
-#endif
 
 	verify_local_APIC();
 	connect_bsp_APIC();
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index 1a6559f..d657558 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -52,7 +52,7 @@ static int __init print_ipi_mode(void)
 }
 late_initcall(print_ipi_mode);
 
-void default_setup_apic_routing(void)
+static void local_default_setup_apic_routing(void)
 {
 #ifdef CONFIG_X86_IO_APIC
 	printk(KERN_INFO
@@ -103,7 +103,7 @@ struct apic apic_default = {
 	.init_apic_ldr			= default_init_apic_ldr,
 
 	.ioapic_phys_id_map		= default_ioapic_phys_id_map,
-	.setup_apic_routing		= default_setup_apic_routing,
+	.setup_apic_routing		= local_default_setup_apic_routing,
 	.multi_timer_check		= NULL,
 	.apicid_to_node			= default_apicid_to_node,
 	.cpu_to_logical_apicid		= default_cpu_to_logical_apicid,
@@ -212,6 +212,22 @@ void __init generic_bigsmp_probe(void)
 #endif
 }
 
+void __init default_setup_apic_routing(void)
+{
+#ifdef CONFIG_X86_BIGSMP
+	/*
+	 * make sure we go to bigsmp according to real nr_cpu_ids
+	 */
+	if (!cmdline_apic && apic == &apic_default) {
+		if (nr_cpu_ids > 8) {
+			apic = &apic_bigsmp;
+			printk(KERN_INFO "Overriding APIC driver with %s\n",
+			       apic->name);
+		}
+	}
+#endif
+}
+
 void __init generic_apic_probe(void)
 {
 	if (!cmdline_apic) {
diff --git a/arch/x86/kernel/apic/probe_64.c b/arch/x86/kernel/apic/probe_64.c
index 450fe20..7dce6f9 100644
--- a/arch/x86/kernel/apic/probe_64.c
+++ b/arch/x86/kernel/apic/probe_64.c
@@ -67,7 +67,11 @@ void __init default_setup_apic_routing(void)
 	}
 #endif
 
-	if (apic == &apic_flat && num_processors > 8)
+	/*
+	 * not just num_processors, we could have hotplug cpus plugged
+	 * in later
+	 */
+	if (apic == &apic_flat && nr_cpu_ids > 8)
 			apic = &apic_physflat;
 
 	printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index eff2fe1..96f5f40 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1083,9 +1083,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 	set_cpu_sibling_map(0);
 
 	enable_IR_x2apic();
-#ifdef CONFIG_X86_64
 	default_setup_apic_routing();
-#endif
 
 	if (smp_sanity_check(max_cpus) < 0) {
 		printk(KERN_INFO "SMP disabled\n");
-- 
1.6.4.2