diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 100c112..3da5e29 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -485,6 +485,9 @@ main(void)
 	/* Initialize sockets thread(s) */
 	soinit1();
 
+	/* This should be before configure() for softint_establish */
+	ipi_sysinit();
+
 	/* Configure the system hardware.  This will enable interrupts. */
 	configure();
 
@@ -499,7 +502,7 @@ main(void)
 
 	configure2();
 
-	ipi_sysinit();
+	ipi_sysinit_ncpu(ncpu);
 
 	/* Now timer is working.  Enable preemption. */
 	kpreempt_enable();
diff --git a/sys/kern/subr_ipi.c b/sys/kern/subr_ipi.c
index 4d26e92..c5dbfc9 100644
--- a/sys/kern/subr_ipi.c
+++ b/sys/kern/subr_ipi.c
@@ -93,20 +93,10 @@ static void		ipi_msg_cpu_handler(void *);
 void
 ipi_sysinit(void)
 {
-	const size_t len = ncpu * sizeof(ipi_mbox_t);
 
-	/* Initialise the per-CPU bit fields. */
-	for (u_int i = 0; i < ncpu; i++) {
-		struct cpu_info *ci = cpu_lookup(i);
-		memset(&ci->ci_ipipend, 0, sizeof(ci->ci_ipipend));
-	}
 	mutex_init(&ipi_mngmt_lock, MUTEX_DEFAULT, IPL_NONE);
 	memset(ipi_intrs, 0, sizeof(ipi_intrs));
 
-	/* Allocate per-CPU IPI mailboxes. */
-	ipi_mboxes = kmem_zalloc(len, KM_SLEEP);
-	KASSERT(ipi_mboxes != NULL);
-
 	/*
 	 * Register the handler for synchronous IPIs.  This mechanism
 	 * is built on top of the asynchronous interface.  Slot zero is
@@ -120,6 +110,25 @@ ipi_sysinit(void)
 }
 
 /*
+ * Must be called after ncpu is determined.
+ */
+void
+ipi_sysinit_ncpu(int _ncpu)
+{
+	const size_t len = _ncpu * sizeof(ipi_mbox_t);
+
+	/* Initialise the per-CPU bit fields. */
+	for (u_int i = 0; i < _ncpu; i++) {
+		struct cpu_info *ci = cpu_lookup(i);
+		memset(&ci->ci_ipipend, 0, sizeof(ci->ci_ipipend));
+	}
+
+	/* Allocate per-CPU IPI mailboxes. */
+	ipi_mboxes = kmem_zalloc(len, KM_SLEEP);
+	KASSERT(ipi_mboxes != NULL);
+}
+
+/*
  * ipi_register: register an asynchronous IPI handler.
  *
  * => Returns IPI ID which is greater than zero; on failure - zero.