1 files changed, 15 insertions, 3 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 42a93621f5b0..951f093a96fe 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1407,9 +1407,21 @@ __init void prefill_possible_map(void)
 {
         int i, possible;
 
-        /* no processor from mptable or madt */
-        if (!num_processors)
-                num_processors = 1;
+        /* No boot processor was found in mptable or ACPI MADT */
+        if (!num_processors) {
+                int apicid = boot_cpu_physical_apicid;
+                int cpu = hard_smp_processor_id();
+
+                pr_warn("Boot CPU (id %d) not listed by BIOS\n", cpu);
+
+                /* Make sure boot cpu is enumerated */
+                if (apic->cpu_present_to_apicid(0) == BAD_APICID &&
+                    apic->apic_id_valid(apicid))
+                        generic_processor_info(apicid, boot_cpu_apic_version);
+
+                if (!num_processors)
+                        num_processors = 1;
+        }
 
         i = setup_max_cpus ?: 1;
         if (setup_possible_cpus == -1) {