we can encounter machines that support pae, but not mwait.
work around this issue.

Reference: /n/atom/patch/applied/paewomwait
Date: Sun May 31 02:33:57 CES 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/pcpae/devarch.c	Sun May 31 02:33:40 2015
+++ /sys/src/9/pcpae/devarch.c	Sun May 31 02:33:42 2015
@@ -688,6 +688,25 @@
 	print(buf);
 }
 
+u64int
+nopmonmwait64(u64int *p, u64int v)
+{
+	if(*p == v)
+		pause();
+	return *p;
+}
+
+u32int
+nopmonmwait32(u32int *p, u32int v)
+{
+	if(*p == v)
+		pause();
+	return *p;
+}
+
+u64int (*monmwait64)(u64int*, u64int) = nopmonmwait64;
+u32int (*monmwait32)(u32int*, u32int) = nopmonmwait32;
+
 /*
  *  figure out:
  *	- cpu type
@@ -698,6 +717,7 @@
  *		(if so turn it on)
  *	- whether or not it supports the page global flag
  *		(if so turn it on)
+ *	- if monmwait is availabile
  */
 int
 cpuidentify(void)
@@ -718,6 +738,10 @@
 	cpuid(Procsig, &regs);
 	m->cpuidax = regs.ax;
 	m->cpuiddx = regs.dx;
+	if(regs.cx & 8){
+//		monmwait64 = k10monmwait64;
+		monmwait32 = k10monmwait32;
+	}
 
 	if(strncmp(m->cpuidid, "AuthenticAMD", 12) == 0 ||
 	   strncmp(m->cpuidid, "Geode by NSC", 12) == 0)