a review of the second edition multiprocessor fs kernels shows that
launchinit was used to launch additional processors.  (on intel these
are called application processors, or APs.)  use the old structure rather
than inventing a new one that has no advantages.

Reference: /n/atom/patch/applied2013/fslaunchamd64
Date: Wed Sep  4 18:43:24 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/fs/ivey/ivey.c	Wed Sep  4 18:42:13 2013
+++ /sys/src/fs/ivey/ivey.c	Wed Sep  4 18:42:13 2013
@@ -65,12 +65,6 @@
 {
 	int i;
 
-	/*
-	 * mutiprocessing.  ta-da!
-	 */
-	sys->epoch = rdtsc();
-	active.thunderbirdsarego = 1;
-
 	settime(rtctime());
 	boottime = time();
 
--- /sys/src/fs/amd64/arch.c	Wed Sep  4 18:42:14 2013
+++ /sys/src/fs/amd64/arch.c	Wed Sep  4 18:42:15 2013
@@ -474,6 +474,17 @@
 void
 launchinit(void)
 {
+	/*
+	 * mutiprocessing.  ta-da!
+	 */
+	sys->epoch = rdtsc();
+	active.thunderbirdsarego = 1;
+}
+
+void
+launchhalt(void)
+{
+	lapicinitaps();
 }
 
 void
--- /sys/src/fs/pc/pc.c	Wed Sep  4 18:42:16 2013
+++ /sys/src/fs/pc/pc.c	Wed Sep  4 18:42:17 2013
@@ -500,6 +500,11 @@
 }
 
 void
+launchhalt(void)
+{
+}
+
+void
 lights(int, int)
 {
 }
--- /sys/src/fs/port/portfns.h	Wed Sep  4 18:42:18 2013
+++ /sys/src/fs/port/portfns.h	Wed Sep  4 18:42:18 2013
@@ -1,3 +1,5 @@
+void	bufprint(int);
+
 void	accessdir(Iobuf*, Dentry*, int, int);
 void	addfree(Device*, Off, Superb*);
 void	arpstart(void);
@@ -48,7 +50,6 @@
 void	dotrace(int);
 void	consinit(void);
 void	consreset(void);
-void	consstart(int);
 int	consgetc(void);
 void	consputs(char*, int);
 void	consserve(void);
@@ -142,6 +143,7 @@
 Devsize	jukesize(Device*);
 void	kbdchar(int);
 void	lights(int, int);
+void	launchhalt(void);
 void	launchinit(void);
 void	localconfinit(void);
 int	leadgroup(int, int);
--- /sys/src/fs/amd64/apic.h	Wed Sep  4 18:42:19 2013
+++ /sys/src/fs/amd64/apic.h	Wed Sep  4 18:42:20 2013
@@ -87,6 +87,7 @@
 void	lapicdump(void);
 int	lapiceoi(int);
 void	lapicinit(int, uintmem, int);
+void	lapicinitaps(void);
 void	lapicipi(int);
 int	lapicisr(int);
 Apic*	lapiclookup(uint);
--- /sys/src/fs/amd64/lapic.c	Wed Sep  4 18:42:21 2013
+++ /sys/src/fs/amd64/lapic.c	Wed Sep  4 18:42:21 2013
@@ -401,6 +401,16 @@
 }
 
 void
+lapicinitaps(void)
+{
+	lapicrput(Ichi, 0);
+	lapicrput(Iclo, DSallexc|TMlevel|Lassert|MTir);
+	microdelay(200);
+	lapicrput(Iclo, DSallexc|TMlevel|MTir);
+	delay(10);
+}
+
+void
 lapicipi(int lapicno)
 {
 	lapicrput(Ichi, lapicno<<24);