From dff8b736bdd75399fb285d430f5900d775bb18e1 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 24 Feb 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-02-24

---
 pc/devlpt.c |  6 +++++-
 pc/l.s      |  2 +-
 pc/trap.c   | 26 +++++++++++++++++---------
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/pc/devlpt.c b/pc/devlpt.c
index 8e152ac8faaf9bea5f108ef3b7e3e01f4f4ceb4d..ae23bbb3feb2461f87becb41bcd51c8d5d7165b9 100644
--- a/pc/devlpt.c
+++ b/pc/devlpt.c
@@ -74,7 +74,6 @@ lptgen(Chan *c, Dirtab *tab, int ntab, int i, Dir *dp)
 void
 lptreset(void)
 {
-	setvec(Parallelvec, lptintr);
 }
 
 void
@@ -86,7 +85,12 @@ lptattach(char *spec)
 {
 	Chan *c;
 	int i  = (spec && *spec) ? strtol(spec, 0, 0) : 1;
+	static int set;
 
+	if(!set){
+		set = 1;
+		setvec(Parallelvec, lptintr);
+	}
 	if(i < 1 || i > NDEV)
 		error(Ebadarg);
 	c = devattach('L', spec);
diff --git a/pc/l.s b/pc/l.s
index 48bb6b7ed75f04798a44640ab90ab32959a6887b..754e1cd3b2695e9e15a5c79a82e69573f9e1a0bc 100644
--- a/pc/l.s
+++ b/pc/l.s
@@ -500,7 +500,7 @@ TEXT	intr31(SB),$0
 	JMP	intrcommon
 TEXT	intr32(SB),$0
 	PUSHL	$0
-	PUSHL	$16
+	PUSHL	$32
 	JMP	intrcommon
 TEXT	intr33(SB),$0
 	PUSHL	$0
diff --git a/pc/trap.c b/pc/trap.c
index 91f961724ab1b7c6c4d9c28189ea213af3fa0c56..0ab10cec82f870caf41130f5633c93eb9314fa45 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -43,7 +43,7 @@ int	int1mask = 0xff;	/* interrupts enabled for second 8259 */
  *  trap/interrupt gates
  */
 Segdesc ilt[256];
-int	badtrap[256];
+int badintr[16];
 
 typedef struct Handler	Handler;
 struct Handler
@@ -245,13 +245,14 @@ trap(Ureg *ur)
 		if(c == Int1vec)
 			outb(Int1ctl, EOI);
 		outb(Int0ctl, EOI);
-		if(v != Uart0vec)
-			uartintr0(ur);
 	}
 
 	if(v>=256 || (h = halloc.ivec[v]) == 0){
+		/* an old 386 generates these fairly often, no idea why */
 		if(v == 13)
 			return;
+
+		/* a processor or coprocessor error */
 		if(v <= 16){
 			if(user){
 				sprint(buf, "sys: trap: %s", excname[v]);
@@ -262,20 +263,27 @@ trap(Ureg *ur)
 				panic("%s pc=0x%lux", excname[v], ur->pc);
 			}
 		}
-		if(badtrap[v]++ < 10 || (badtrap[v]%1000) == 0)
-			print("bad trap type %d pc=0x%lux: total %d\n", v, ur->pc,
-				badtrap[v]);
+
+		if(v >= Int0vec || v < Int0vec+16){
+			/* an unknown interrupts */
+			v -= Int0vec;
+			if(badintr[v]++ == 0 || (badintr[v]%1000) == 0)
+				print("unknown interrupt %d pc=0x%lux: total %d\n", v,
+					ur->pc, badintr[v]);
+		} else {
+			/* unimplemented traps */
+			print("illegal trap %d pc=0x%lux\n", v, ur->pc);
+		}
 		return;
 	}
 
+	/* there may be multiple handlers on one interrupt level */
 	do {
 		(*h->r)(ur);
 		h = h->next;
 	} while(h);
 
-	/*
-	 *  check user since syscall does its own notifying
-	 */
+	/* check user since syscall does its own notifying */
 	if(user && (u->p->procctl || u->nnote))
 		notify(ur);
 }