From 5affa3702322081b506ce03d2fe143463466fdb1 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Thu, 13 Jul 2000 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2000-07-13

---
 alphapc/devether.c |  8 ++++----
 carrera/devether.c |  8 ++++----
 mpc/devether.c     |  8 ++++----
 pc/devether.c      |  8 ++++----
 pc/i8253.c         | 11 +++++++++--
 5 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/alphapc/devether.c b/alphapc/devether.c
index fc9e06889f787b35b41f405311652b5a78b6c2b4..f6406ee891d8938670e525229881ed5c2273ce21 100644
--- a/alphapc/devether.c
+++ b/alphapc/devether.c
@@ -110,12 +110,12 @@ etherrtrace(Netfile* f, Etherpkt* pkt, int len)
 
 	if(qwindow(f->in) <= 0)
 		return;
-	if(len > 64)
-		n = 64;
+	if(len > 58)
+		n = 58;
 	else
 		n = len;
-	bp = iallocb(n);
-	if(bp == 0)
+	bp = iallocb(64);
+	if(bp == nil)
 		return;
 	memmove(bp->wp, pkt->d, n);
 	i = TK2MS(MACHP(0)->ticks);
diff --git a/carrera/devether.c b/carrera/devether.c
index e6e35fcb84660bbd41266d582cbffe707e76a604..20053c00a119c911405a2faceaab3da81b8d0046 100644
--- a/carrera/devether.c
+++ b/carrera/devether.c
@@ -110,12 +110,12 @@ etherrtrace(Netfile* f, Etherpkt* pkt, int len)
 
 	if(qwindow(f->in) <= 0)
 		return;
-	if(len > 64)
-		n = 64;
+	if(len > 58)
+		n = 58;
 	else
 		n = len;
-	bp = iallocb(n);
-	if(bp == 0)
+	bp = iallocb(64);
+	if(bp == nil)
 		return;
 	memmove(bp->wp, pkt->d, n);
 	i = TK2MS(MACHP(0)->ticks);
diff --git a/mpc/devether.c b/mpc/devether.c
index 4334bf9559d6f64b3d8e5797b164e9193357a0b6..4dd3d9812fce3b731243cef8b81483c6a8e19dff 100644
--- a/mpc/devether.c
+++ b/mpc/devether.c
@@ -110,12 +110,12 @@ etherrtrace(Netfile* f, Etherpkt* pkt, int len)
 
 	if(qwindow(f->in) <= 0)
 		return;
-	if(len > 64)
-		n = 64;
+	if(len > 58)
+		n = 58;
 	else
 		n = len;
-	bp = iallocb(n);
-	if(bp == 0)
+	bp = iallocb(64);
+	if(bp == nil)
 		return;
 	memmove(bp->wp, pkt->d, n);
 	i = TK2MS(MACHP(0)->ticks);
diff --git a/pc/devether.c b/pc/devether.c
index fc9e06889f787b35b41f405311652b5a78b6c2b4..f6406ee891d8938670e525229881ed5c2273ce21 100644
--- a/pc/devether.c
+++ b/pc/devether.c
@@ -110,12 +110,12 @@ etherrtrace(Netfile* f, Etherpkt* pkt, int len)
 
 	if(qwindow(f->in) <= 0)
 		return;
-	if(len > 64)
-		n = 64;
+	if(len > 58)
+		n = 58;
 	else
 		n = len;
-	bp = iallocb(n);
-	if(bp == 0)
+	bp = iallocb(64);
+	if(bp == nil)
 		return;
 	memmove(bp->wp, pkt->d, n);
 	i = TK2MS(MACHP(0)->ticks);
diff --git a/pc/i8253.c b/pc/i8253.c
index 63d94b95b93619ed9ad556820a44acc271dae6c2..4c38c6fccb21b9a31b3fcf0f8651e752796f310e 100644
--- a/pc/i8253.c
+++ b/pc/i8253.c
@@ -55,6 +55,7 @@ enum
 static struct
 {
 	Lock;
+	int	havecyc;
 	int	enabled;
 	int	mode;
 	vlong	when;		/* next fastticks a clock interrupt should occur */
@@ -72,6 +73,7 @@ i8253init(int aalcycles, int havecycleclock)
 
 	if(initialised == 0){
 		initialised = 1;
+		i8253.havecyc = havecycleclock;
 		ioalloc(T0cntr, 4, 0, "i8253");
 		ioalloc(T2ctl, 1, 0, "i8253.cntr2ctl");
 
@@ -204,7 +206,7 @@ clockintrsched0(vlong next)
 int
 havecycintr(void)
 {
-	return i8253.enabled;
+	return i8253.havecyc && i8253.enabled;
 }
 
 void
@@ -213,7 +215,7 @@ clockintrsched(void)
 	vlong next;
 
 	ilock(&i8253);
-	if(i8253.enabled){
+	if(i8253.enabled && i8253.havecyc){
 		next = cycintrnext();
 		if(next != i8253.cycwhen)
 			clockintrsched0(next);
@@ -226,6 +228,11 @@ clockintr0(Ureg* ureg, void *v)
 {
 	vlong now, when;
 
+	if(!i8253.havecyc){
+		clockintr(ureg, v);
+		return;
+	}
+
 	now = fastticks(nil);
 	when = i8253.when;
 	if(now >= i8253.when){