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-rw-r--r--arch/x86/kernel/apic/io_apic.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 4abf08aab3d..8a0215042a5 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2007,9 +2007,12 @@ void __init setup_ioapic_ids_from_mpc_nocheck(void)
= mp_ioapics[apic_id].apicid;
/*
- * Read the right value from the MPC table and
- * write it into the ID register.
+ * Update the ID register according to the right value
+ * from the MPC table if they are different.
*/
+ if (mp_ioapics[apic_id].apicid == reg_00.bits.ID)
+ continue;
+
apic_printk(APIC_VERBOSE, KERN_INFO
"...changing IO-APIC physical APIC ID to %d ...",
mp_ioapics[apic_id].apicid);