[PATCH] x86: fix 2.6.27rc1 cannot boot more than 8CPUs

[Yinghai Lu]

Jeff Chua reported that booting a !bigsmp kernel on a 16-way box
hangs silently.

this is a long-standing issue, smp start AP cpu could check the
apic id >=8 etc before trying to start it.

achieve this by moving the def_to_bigsmp check later and skip the
apicid id > 8

[ mingo@xxxxxxx: clean up the message that is printed. ]

Reported-by: "Jeff Chua" <jeff.chua.linux@xxxxxxxxx>
Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

 arch/x86/kernel/setup.c   |    6 ------
 arch/x86/kernel/smpboot.c |   10 ++++++++++
 2 files changed, 10 insertions(+), 6 deletions(-)
---
 arch/x86/kernel/setup.c   |    6 ------
 arch/x86/kernel/smpboot.c |   10 ++++++++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 6e5823b..68b48e3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -861,12 +861,6 @@ void __init setup_arch(char **cmdline_p)
 	init_apic_mappings();
 	ioapic_init_mappings();
 
-#if defined(CONFIG_SMP) && defined(CONFIG_X86_PC) && defined(CONFIG_X86_32)
-	if (def_to_bigsmp)
-		printk(KERN_WARNING "More than 8 CPUs detected and "
-			"CONFIG_X86_PC cannot handle it.\nUse "
-			"CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP.\n");
-#endif
 	kvm_guest_init();
 
 	e820_reserve_resources();
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index da10f07..91055d7 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -994,7 +994,17 @@ int __cpuinit native_cpu_up(unsigned int cpu)
 	flush_tlb_all();
 	low_mappings = 1;
 
+#ifdef CONFIG_X86_PC
+	if (def_to_bigsmp && apicid > 8) {
+		printk(KERN_WARNING
+			"More than 8 CPUs detected - skipping them.\n"
+			"Use CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP.\n");
+		err = -1;
+	} else
+		err = do_boot_cpu(apicid, cpu);
+#else
 	err = do_boot_cpu(apicid, cpu);
+#endif
 
 	zap_low_mappings();
 	low_mappings = 0;
--
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