From 4fa8390216a31b5fd8cfcaf1c51fb62ef5a35c5e Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 6 Jan 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-01-06

---
 pc/devvga.c  | 29 +++++++++++++++++++++++------
 power/l.s    | 14 +++++++-------
 power/main.c |  2 +-
 power/trap.c | 24 ++++++++++++------------
 4 files changed, 43 insertions(+), 26 deletions(-)

diff --git a/pc/devvga.c b/pc/devvga.c
index 1685f989657ec161e27656abb5dbe13fe3d3ecb2..75726f5d3b1344db03b3ebde107b6bda7d146e5d 100644
--- a/pc/devvga.c
+++ b/pc/devvga.c
@@ -103,6 +103,7 @@ VGAmode mode13 =
 static	Rectangle mbb;
 static	Rectangle NULLMBB = {10000, 10000, -10000, -10000};
 static	void nopage(int), tsengpage(int), tridentpage(int), parapage(int);
+static	void atipage(int);
 static	void vgaupdate(void);
 
 /*
@@ -124,9 +125,9 @@ enum
 	Generic,
 };
 
-Vgacard vgacards[] =
+Vgacard vgachips[] =
 {
-[Ati]		{ "ati", nopage, },
+[Ati]		{ "ati", atipage, },
 [Pvga1a]	{ "pvga1a", parapage, },
 [Trident]	{ "trident", tridentpage, },
 [Tseng]		{ "tseng", tsengpage, },
@@ -145,7 +146,7 @@ enum
 	Qvgasize=	1,
 	Qvgatype=	2,
 	Qvgaport=	3,
-	Nvga=		4,
+	Nvga=		3,
 };
 Dirtab vgadir[]={
 	"vgasize",	{Qvgasize},	0,		0666,
@@ -156,7 +157,7 @@ Dirtab vgadir[]={
 void
 vgareset(void)
 {
-	vgacard = &vgacards[Generic];
+	vgacard = &vgachips[Generic];
 }
 
 void
@@ -253,7 +254,7 @@ vgawrite(Chan *c, void *buf, long n, ulong offset)
 		cbuf[n] = 0;
 		if(cp = strchr(cbuf, '\n'))
 			*cp = 0;
-		for(vp = vgacards; vp->name; vp++)
+		for(vp = vgachips; vp->name; vp++)
 			if(strcmp(cbuf, vp->name) == 0){
 				vgacard = vp;
 				return n;
@@ -629,10 +630,26 @@ nopage(int page)
 {
 	USED(page);
 }
+/*
+ * The following code is unproven: we haven't got the
+ * ATI stuff to work yet.
+ */
+static void
+atipage(int page)
+{
+	/* the ext register is in the ATI ROM at a fixed address */
+	ushort extreg = *((ushort *)0x800C0010);
+	uchar v;
+
+	outb(extreg, 0xb2);
+	v = (inb(extreg+1) & 0xe1) | (page<<1);
+	outb(extreg, 0xb2);
+	outb(extreg+1, v);
+}
 static void
 tridentpage(int page)
 {
-	srout(0x0e, page^0x02);	/* yes, the page bit needs to be toggled! */
+	srout(0x0e, page^0x02);
 }
 static void
 tsengpage(int page)
diff --git a/power/l.s b/power/l.s
index d4e2b298232bc73efcbd6e887e80b1b896f71f00..f00def7d7f6cd0798aaa20760ef5dc0a2037a2d1 100644
--- a/power/l.s
+++ b/power/l.s
@@ -493,19 +493,18 @@ TEXT	clrfpintr(SB), $0
 	OR	$CU1, R3
 	MOVW	R3, M(STATUS)
 	WAIT
-
-	MOVW	FCR31, R1
-	MOVW	R1, R2
-	AND	$~(0x3F<<12), R2
-	MOVW	R2, FCR31
-
+	MOVW	FCR31, R1		/* Read it to stall the fpu */
+	WAIT
+	MOVW	R0, FCR31
+	WAIT
 	AND	$~CU1, R3
 	MOVW	R3, M(STATUS)
 	RET
 
 TEXT	savefpregs(SB), $0
 	MOVW	M(STATUS), R3
-	MOVW	FCR31, R2
+	MOVW	FCR31, R2		/* Read stalls the fpu until inst. complete. */
+	WAIT
 
 	MOVD	F0, 0x00(R1)
 	MOVD	F2, 0x08(R1)
@@ -523,6 +522,7 @@ TEXT	savefpregs(SB), $0
 	MOVD	F26, 0x68(R1)
 	MOVD	F28, 0x70(R1)
 	MOVD	F30, 0x78(R1)
+	WAIT
 
 	MOVW	R2, 0x80(R1)
 	AND	$~CU1, R3
diff --git a/power/main.c b/power/main.c
index 315aa0c6e1a4c8e2fba220a6c38442c9d706e67d..1feb5b9e3296b9688479c06b54e56d9cf0d1d5ce 100644
--- a/power/main.c
+++ b/power/main.c
@@ -537,7 +537,7 @@ confinit(void)
 	/*
 	 *  set minimal default values
 	 */
-	conf.nmach = 1;
+	conf.nmach = 2;
 	conf.nproc = 100;
 	conf.nswap = 262144;
 	conf.nimage = 200;
diff --git a/power/trap.c b/power/trap.c
index 6e01ced2fbcbf8f8db245bd6900732c8ba81929b..374546d0331dfdb847956e71bcaa091864527df2 100644
--- a/power/trap.c
+++ b/power/trap.c
@@ -76,18 +76,18 @@ m->ur = ur;
 
 	ecode = (ur->cause>>2)&0xf;
 	user = ur->status&KUP;
-	if(user)
-		u->dbgreg = ur;
-
 	fpchk = 0;
-	if(u && u->p->fpstate == FPactive) {
-		if((ur->status&CU1) == 0)		/* Paranoid */
-			panic("FPactive but no CU1");
-		u->p->fpstate = FPinactive;
-		ur->status &= ~CU1;
-		savefpregs(&u->fpsave);
-		fptrap(ur);
-		fpchk = 1;
+	if(user) {
+		u->dbgreg = ur;
+		if(u->p->fpstate == FPactive) {
+			if((ur->status&CU1) == 0)		/* Paranoid */
+				panic("FPactive but no CU1");
+			u->p->fpstate = FPinactive;
+			ur->status &= ~CU1;
+			savefpregs(&u->fpsave);
+			fptrap(ur);
+			fpchk = 1;
+		}
 	}
 
 	switch(ecode){
@@ -115,7 +115,7 @@ m->ur = ur;
 
 	case CCPU:
 		cop = (ur->cause>>28)&3;
-		if(user && u && cop == 1) {
+		if(user && cop == 1) {
 			if(u->p->fpstate == FPinit) {
 				u->p->fpstate = FPinactive;
 				fcr31 = u->fpsave.fpstatus;