Commit ff856051 authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Ingo Molnar
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x86/boot/smp: Don't try to poke disabled/non-existent APIC

Apparently trying to poke a disabled or non-existent APIC
leads to a box that doesn't even boot. Let's not do that.

No real clue if this is the right fix, but at least my
P3 machine boots again.
Signed-off-by: default avatarVille Syrjälä <>
Cc: Andy Lutomirski <>
Cc: Borislav Petkov <>
Cc: Borislav Petkov <>
Cc: Brian Gerst <>
Cc: Denys Vlasenko <>
Cc: Eric Biederman <>
Cc: H. Peter Anvin <>
Cc: Jiri Olsa <>
Cc: Josh Poimboeuf <>
Cc: Juergen Gross <>
Cc: Len Brown <>
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Prarit Bhargava <>
Cc: Thomas Gleixner <>
Cc: Yinghai Lu <>
Fixes: 2a51fe08 ("arch/x86: Handle non enumerated CPU after physical hotplug")

Signed-off-by: default avatarIngo Molnar <>
parent c8061485
......@@ -1409,6 +1409,7 @@ __init void prefill_possible_map(void)
/* No boot processor was found in mptable or ACPI MADT */
if (!num_processors) {
if (boot_cpu_has(X86_FEATURE_APIC)) {
int apicid = boot_cpu_physical_apicid;
int cpu = hard_smp_processor_id();
......@@ -1418,6 +1419,7 @@ __init void prefill_possible_map(void)
if (apic->cpu_present_to_apicid(0) == BAD_APICID &&
generic_processor_info(apicid, boot_cpu_apic_version);
if (!num_processors)
num_processors = 1;
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