diff --git a/sys/ia64/ia64/genassym.c b/sys/ia64/ia64/genassym.c
index 8e988b675452..4a192fd79e39 100644
--- a/sys/ia64/ia64/genassym.c
+++ b/sys/ia64/ia64/genassym.c
@@ -91,7 +91,6 @@ ASSYM(MC_SPECIAL_RNAT,	offsetof(mcontext_t, mc_special.rnat));
 ASSYM(PAGE_SHIFT,	PAGE_SHIFT);
 ASSYM(PAGE_SIZE,	PAGE_SIZE);
 
-ASSYM(PC_CPUID,		offsetof(struct pcpu, pc_cpuid));
 ASSYM(PC_CURRENT_PMAP,	offsetof(struct pcpu, pc_current_pmap));
 ASSYM(PC_CURTHREAD,	offsetof(struct pcpu, pc_curthread));
 ASSYM(PC_IDLETHREAD,	offsetof(struct pcpu, pc_idlethread));
diff --git a/sys/ia64/ia64/machdep.c b/sys/ia64/ia64/machdep.c
index b1e7298fa96e..67ca3c28c497 100644
--- a/sys/ia64/ia64/machdep.c
+++ b/sys/ia64/ia64/machdep.c
@@ -424,7 +424,11 @@ void
 cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
 {
 
-	pcpu->pc_acpi_id = cpuid;
+	/*
+	 * Set pc_acpi_id to "uninitialized".
+	 * See sys/dev/acpica/acpi_cpu.c
+	 */
+	pcpu->pc_acpi_id = 0xffffffff;
 }
 
 void
diff --git a/sys/ia64/ia64/mp_machdep.c b/sys/ia64/ia64/mp_machdep.c
index e94acadd2358..92e26216e48b 100644
--- a/sys/ia64/ia64/mp_machdep.c
+++ b/sys/ia64/ia64/mp_machdep.c
@@ -208,31 +208,25 @@ cpu_mp_add(u_int acpiid, u_int apicid, u_int apiceid)
 	struct pcpu *pc;
 	u_int64_t lid;
 	void *dpcpu;
-
-	/* Ignore any processor numbers outside our range */
-	if (acpiid > mp_maxid)
-		return;
-
-	KASSERT((all_cpus & (1UL << acpiid)) == 0,
-	    ("%s: cpu%d already in CPU map", __func__, acpiid));
+	u_int cpuid;
 
 	lid = LID_SAPIC_SET(apicid, apiceid);
+	cpuid = ((ia64_get_lid() & LID_SAPIC_MASK) == lid) ? 0 : smp_cpus++;
 
-	if ((ia64_get_lid() & LID_SAPIC_MASK) == lid) {
-		KASSERT(acpiid == 0,
-		    ("%s: the BSP must be cpu0", __func__));
-	}
+	KASSERT((all_cpus & (1UL << cpuid)) == 0,
+	    ("%s: cpu%d already in CPU map", __func__, acpiid));
 
-	if (acpiid != 0) {
+	if (cpuid != 0) {
 		pc = (struct pcpu *)malloc(sizeof(*pc), M_SMP, M_WAITOK);
+		pcpu_init(pc, cpuid, sizeof(*pc));
 		dpcpu = (void *)kmem_alloc(kernel_map, DPCPU_SIZE);
-		pcpu_init(pc, acpiid, sizeof(*pc));
-		dpcpu_init(dpcpu, acpiid);
+		dpcpu_init(dpcpu, cpuid);
 	} else
 		pc = pcpup;
 
+	pc->pc_acpi_id = acpiid;
 	pc->pc_lid = lid;
-	all_cpus |= (1UL << acpiid);
+	all_cpus |= (1UL << cpuid);
 }
 
 void
@@ -244,8 +238,8 @@ cpu_mp_announce()
 	for (i = 0; i <= mp_maxid; i++) {
 		pc = pcpu_find(i);
 		if (pc != NULL) {
-			printf("cpu%d: SAPIC Id=%x, SAPIC Eid=%x", i,
-			    LID_SAPIC_ID(pc->pc_lid),
+			printf("cpu%d: ACPI Id=%x, SAPIC Id=%x, SAPIC Eid=%x",
+			    i, pc->pc_acpi_id, LID_SAPIC_ID(pc->pc_lid),
 			    LID_SAPIC_EID(pc->pc_lid));
 			if (i == 0)
 				printf(" (BSP)\n");
@@ -305,7 +299,9 @@ cpu_mp_unleash(void *dummy)
 	SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
 		cpus++;
 		if (pc->pc_awake) {
-			kproc_create(ia64_store_mca_state, (void*)((uintptr_t)pc->pc_cpuid), NULL, 0, 0, "mca %u", pc->pc_cpuid);
+			kproc_create(ia64_store_mca_state,
+			    (void*)((uintptr_t)pc->pc_cpuid), NULL, 0, 0,
+			    "mca %u", pc->pc_cpuid);
 			smp_cpus++;
 		}
 	}