[PATCH] x86_64: Dont record local apic ids when they are disabled in MADT

Some broken BIOS's had processors disabled, but
same apic id as a valid processor. This causes
acpi_processor_start() to think this disabled
cpu is ok, and croak. So we dont record bad
apicid's anymore.

http://bugzilla.kernel.org/show_bug.cgi?id=5930

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/acpi/boot.c b/arch/i386/kernel/acpi/boot.c
index f21fa0d..79577f0 100644 (file)
--- a/arch/i386/kernel/acpi/boot.c
+++ b/arch/i386/kernel/acpi/boot.c
@@ -248,10 +248,17 @@ acpi_parse_lapic(acpi_table_entry_header * header, const unsigned long end)
 
        acpi_table_print_madt_entry(header);
 
-       /* Register even disabled CPUs for cpu hotplug */
-
-       x86_acpiid_to_apicid[processor->acpi_id] = processor->id;
+       /* Record local apic id only when enabled */
+       if (processor->flags.enabled)
+               x86_acpiid_to_apicid[processor->acpi_id] = processor->id;
 
+       /*
+        * We need to register disabled CPU as well to permit
+        * counting disabled CPUs. This allows us to size
+        * cpus_possible_map more accurately, to permit
+        * to not preallocating memory for all NR_CPUS
+        * when we use CPU hotplug.
+        */
        mp_register_lapic(processor->id,        /* APIC ID */
                          processor->flags.enabled);    /* Enabled? */