From b020507a84c1ed321d019e4551b60a766bf11a71 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 17 Feb 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-02-17

---
 pc/main.c   |  5 +++--
 pc/trap.c   | 37 +++++++++++++++++++++++++++++++++----
 ss/screen.c |  2 +-
 3 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/pc/main.c b/pc/main.c
index 0ac06890bfb7dcc265edbdd2d53e9abbdbc76009..164e22864c1b8df67e0fb06a2a674bd9ba228075 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -264,6 +264,7 @@ confinit(void)
 		l--;
 		if(*l != x)
 			break;
+		memset((char*)(KZERO|((i-1)*MB)), 0, MB);
 		x += 0x3141526;
 	}
 	i--;
@@ -275,8 +276,8 @@ confinit(void)
 	pcnt = (1<<conf.ldepth)-1;		/* Calculate % of memory for page pool */
 	pcnt = 70 - (pcnt*10);
 	conf.upages = (conf.npage*pcnt)/100;
-	if(conf.npage - conf.upages < (2*MB)/BY2PG)
-		conf.upages = conf.npage - (2*MB)/BY2PG;
+	if(conf.npage - conf.upages < ((3*MB)/4)/BY2PG)
+		conf.upages = conf.npage - ((3*MB)/4)/BY2PG;
 
 	ktop = PGROUND((ulong)end);
 	ktop = PADDR(ktop);
diff --git a/pc/trap.c b/pc/trap.c
index 984d1e265c3c55d01c0d270976b3a0a711bd60b2..2ee04ab13e57c19ee9a9dbade9ecb1b670459abb 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -32,6 +32,8 @@ enum
 	Int1aux=	0xA1,		/* everything else (ICW2, ICW3, ICW4, OCW1) */
 
 	EOI=		0x20,		/* non-specific end of interrupt */
+
+	Maxhandler=	128,		/* max number of interrupt handlers */
 };
 
 int	int0mask = 0xff;	/* interrupts enabled for first 8259 */
@@ -41,7 +43,21 @@ int	int1mask = 0xff;	/* interrupts enabled for second 8259 */
  *  trap/interrupt gates
  */
 Segdesc ilt[256];
-void	(*ivec[256])(void*);
+
+typedef struct Handler	Handler;
+struct Handler
+{
+	void	(*r)(void*);
+	Handler	*next;
+};
+
+struct
+{
+	Lock;
+	Handler	*ivec[256];
+	Handler	h[Maxhandler];
+	int	free;
+} halloc;
 
 void
 sethvec(int v, void (*r)(void), int type, int pri)
@@ -53,7 +69,16 @@ sethvec(int v, void (*r)(void), int type, int pri)
 void
 setvec(int v, void (*r)(Ureg*))
 {
-	ivec[v] = r;
+	Handler *h;
+
+	lock(&halloc);
+	if(halloc.free >= Maxhandler)
+		panic("out of interrupt handlers");
+	h = &halloc.h[halloc.free++];
+	h->next = halloc.ivec[v];
+	h->r = r;
+	halloc.ivec[v] = h;
+	unlock(&halloc);
 
 	/*
 	 *  enable corresponding interrupt in 8259
@@ -201,6 +226,7 @@ trap(Ureg *ur)
 	int v, user;
 	int c;
 	char buf[ERRLEN];
+	Handler *h;
 
 	v = ur->trap;
 
@@ -222,7 +248,7 @@ trap(Ureg *ur)
 			uartintr0(ur);
 	}
 
-	if(v>=256 || ivec[v] == 0){
+	if(v>=256 || (h = halloc.ivec[v]) == 0){
 		if(v == 13)
 			return;
 		if(v <= 16){
@@ -239,7 +265,10 @@ trap(Ureg *ur)
 		return;
 	}
 
-	(*ivec[v])(ur);
+	do {
+		(*h->r)(ur);
+		h = h->next;
+	} while(h);
 
 	/*
 	 *  check user since syscall does its own notifying
diff --git a/ss/screen.c b/ss/screen.c
index 5847d5892d361aabf3fcf6cce8e967682b40280a..90fc155fc8358a04dacc729024a29db408f8917f 100644
--- a/ss/screen.c
+++ b/ss/screen.c
@@ -69,7 +69,7 @@ struct screens
 }screens[] = {
 	{ "bwtwo", 1152, 900, 0, 0x400000 },
 	{ "cgsix", 1152, 900, 3, 0x200000 },
-	{ "cgthree", 1152, 900, 3, 0x200000 },	/* PURE GUESS! */
+	{ "cgthree", 1152, 900, 3, 0x400000 },	/* data from rwolff */
 	0
 };