From c054d30736657f9a69f65d320ab94b47344ec036 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 17 Aug 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-08-17

---
 carrera/clock.c |  2 +-
 carrera/trap.c  |  5 +++++
 pc/fns.h        |  2 ++
 pc/main.c       | 19 ++-----------------
 pc/mem.h        |  5 -----
 pc/trap.c       | 33 ---------------------------------
 port/cache.c    |  2 ++
 port/devproc.c  | 20 ++++++++++----------
 port/page.c     |  8 +++-----
 port/portdat.h  |  5 ++++-
 port/portfns.h  |  2 +-
 port/proc.c     | 11 +++++++++--
 port/segment.c  |  4 ++--
 port/swap.c     |  2 ++
 port/sysproc.c  |  4 ++--
 15 files changed, 45 insertions(+), 79 deletions(-)

diff --git a/carrera/clock.c b/carrera/clock.c
index 3949a0b154954a142029f8d86679ee6a3d947db2..4c2db468d23f867127cdada3646369e35a49d035 100644
--- a/carrera/clock.c
+++ b/carrera/clock.c
@@ -93,7 +93,7 @@ clock(Ureg *ur)
 	checkalarms();
 	mouseclock();
 
-	if(up == 0 || (ur->status&IE) == 0 || up->state != Running)
+	if(up == 0 || up->state != Running)
 		return;
 
 	if(anyready())
diff --git a/carrera/trap.c b/carrera/trap.c
index f1ad5c21af155c6c2ecf8cf4e382f1cc05a2bfa7..a3890a8d61e561114a68ae88023b4de90f96195f 100644
--- a/carrera/trap.c
+++ b/carrera/trap.c
@@ -361,12 +361,17 @@ intr(Ureg *ur)
 	if(cause & INTR7) {
 		clock(ur);
 		cause &= ~INTR7;
+		return;
 	}
 
 	if(cause) {
 		iprint("cause %lux\n", cause);
 		exit(1);
 	}
+
+	/* preemptive scheduling */
+	if(up && up->state == Running && anyhigher())
+		sched();
 }
 
 char*
diff --git a/pc/fns.h b/pc/fns.h
index c73bbadca4f881fe97bd17e16d5eac11790fea57..a4403daedbff864917f7b44c95c741a8c9cab25d 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -87,6 +87,8 @@ int	tas(void*);
 void	uartclock(void);
 void	uartpoll(void);
 void	vgainit(void);
+void	vgasavecrash(uchar*, int);
+void	vgarestorecrash(uchar*, int);
 int	x86(void);
 
 #define	waserror()	(up->nerrlab++, setlabel(&up->errlab[up->nerrlab-1]))
diff --git a/pc/main.c b/pc/main.c
index 33c8e7b2e84d80af2c339029c66e6b1bf4abef1b..e6031e1902cef0c7c50b01b2c1463380342125a9 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -390,20 +390,13 @@ confinit(void)
 	}
 
 	/*
-	 *  zero and clear all except first 2 meg and crash area.
-	 *  put crash area at high end of memory.
+	 *  zero and clear all except first 2 meg.
 	 */
 	x = 0x12345678;
 	for(i = MAXMEG; i > 1; i--){
 		if(mmap[i] != 'x')
 			continue;
-		j = MB;
-		if(crasharea == 0){
-			crasharea = (i+1)*MB - PGROUND(CRASHSIZE);
-			crashend = crasharea + CRASHSIZE;
-			j = MB - PGROUND(CRASHSIZE);
-		}
-		if(memclrtest(i, j, x) < 0)
+		if(memclrtest(i, MB, x) < 0)
 			mmap[i] = ' ';
 		x += 0x3141526;
 	}
@@ -418,8 +411,6 @@ confinit(void)
 		;
 	conf.npage0 = (i*MB - ktop)/BY2PG;
 	conf.topofmem = i*MB;
-	if(crasharea < conf.base0 + BY2PG*conf.npage0)
-		conf.npage0 -= PGROUND(CRASHSIZE)/BY2PG;
 
 	/*
 	 *  bank1 usually goes from the end of BOOTARGS to 640k
@@ -441,15 +432,9 @@ confinit(void)
 				;
 			conf.npage1 = (j - i)*MB/BY2PG;
 			conf.topofmem = j*MB;
-			if(crasharea < conf.base1 + BY2PG*conf.npage1)
-				conf.npage1 -= PGROUND(CRASHSIZE)/BY2PG;
 			break;
 		}
 
-	/* make crasharea a virtual address */
-	crasharea |= KZERO;
-	crashend |= KZERO;
-
 	conf.npage = conf.npage0 + conf.npage1;
 	conf.ldepth = 0;
 	if(pcnt < 10)
diff --git a/pc/mem.h b/pc/mem.h
index 4e9680c2bc343390eb60768641c71c4ab2422ad8..6db6f9fbfe38502cd8d8bf88600bd8f6d4e733df 100644
--- a/pc/mem.h
+++ b/pc/mem.h
@@ -55,11 +55,6 @@
 
 #define	MACHSIZE	4096
 
-/*
- *  an area for storing crash info to be picked up later
- */
-#define CRASHSIZE	(KSTACK+BY2PG)
-
 /*
  *  known 80386 segments (in GDT) and their selectors
  */
diff --git a/pc/trap.c b/pc/trap.c
index 5a1cc7a0bb51acf880c50848fee75bd932e52b7a..d1d2338e6d459aefba3ea5933e900c6b300248de 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -61,19 +61,6 @@ struct
 	int	free;
 } halloc;
 
-/*
- *  somewhere to drop crash info
- */
-typedef struct
-{
-	ulong	magic;
-	void	*kbot;
-	void	*ksp;
-	char	text[NAMELEN];
-	Ureg	ureg;
-	uchar	kstack[KSTACK];
-} Crashstate;
-
 void
 sethvec(int v, void (*r)(void), int type, int pri)
 {
@@ -353,7 +340,6 @@ dumpregs2(Ureg *ur)
 void
 dumpregs(Ureg *ur)
 {
-	Crashstate *cs;
 	extern ulong etext;
 	ulong *x;
 
@@ -362,13 +348,6 @@ dumpregs(Ureg *ur)
 	dumpregs2(ur);
 	print("  magic %lux %lux %lux\n", x[0], x[1], x[2]);
 	print("  ur %lux up %lux\n", ur, up);
-
-	/* save crash info */
-	if(crasharea == 0)
-		return;
-	print("crasharea 0x%lux\n", crasharea);
-	cs = (Crashstate*)crasharea;
-	memmove(&cs->ureg, ur, sizeof(Ureg));
 }
 
 void
@@ -376,7 +355,6 @@ dumpstack(void)
 {
 	ulong l, v, i;
 	extern ulong etext;
-	Crashstate *cs;
 
 	if(up == 0)
 		return;
@@ -393,17 +371,6 @@ dumpstack(void)
 			print("\n");
 		}
 	}
-
-	/* save crash info */
-	if(crasharea == 0)
-		return;
-	print("crasharea 0x%lux\n", crasharea);
-	cs = (Crashstate*)crasharea;
-	memmove(cs->kstack, up->kstack, KSTACK);
-	cs->kbot = up->kstack;
-	memmove(cs->text, up->text, NAMELEN);
-	cs->magic = 0xdeaddead;
-	cs->ksp = &l;
 }
 
 /*
diff --git a/port/cache.c b/port/cache.c
index 5f61f76ec8c53aefba0cc2b6e2c1ad8478201780..91760b18672400b58399002d6e21e37c21a570b2 100644
--- a/port/cache.c
+++ b/port/cache.c
@@ -67,6 +67,8 @@ cinit(void)
 	cache.tail = m;
 	cache.tail->next = 0;
 	cache.head->prev = 0;
+
+	fscache.notext = 1;
 }
 
 void
diff --git a/port/devproc.c b/port/devproc.c
index 42fa5b5159ca55399b41bace2639547a7cc98383..478d0fba8946af54a0a8b7387ccd210c53b0bafc 100644
--- a/port/devproc.c
+++ b/port/devproc.c
@@ -49,10 +49,6 @@ Dirtab procdir[] =
 /* Segment type from portdat.h */
 char *sname[]={ "Text", "Data", "Bss", "Stack", "Shared", "Phys", "Shdata" };
 
-/* where to put crash information when memory isn't wiped */
-ulong crasharea;
-ulong crashend;
-
 /*
  * Qids are, in path:
  *	 4 bits of file type (qids above)
@@ -318,12 +314,6 @@ procread(Chan *c, void *va, long n, ulong offset)
 			memmove(a, (char*)offset, n);
 			return n;
 		}
-		if(offset >= crasharea && offset < crashend){
-			if(offset+n > crashend)
-				n = crashend - offset;
-			memmove(a, (char*)offset, n);
-			return n;
-		}
 		error(Ebadarg);
 
 	case Qnote:
@@ -697,6 +687,7 @@ void
 procctlreq(Proc *p, char *va, int n)
 {
 	char buf[NAMELEN];
+	int i;
 
 	if(n > NAMELEN)
 		n = NAMELEN;
@@ -743,6 +734,15 @@ procctlreq(Proc *p, char *va, int n)
 			error(Ebadctl);
 		ready(p);
 	}
+	else
+	if(strncmp(buf, "pri", 3) == 0){
+		if(n < 4)
+			error(Ebadarg);
+		i = atoi(buf+4);
+		if(i < 0 || i >= Nrq)
+			error(Ebadarg);
+		p->basepri = i;
+	}
 	else
 		error(Ebadctl);
 }
diff --git a/port/page.c b/port/page.c
index 736576a1ffbc6ad41649ce10c6207287adf95066..df12d3568a5bbbc02482fd5519cfd345f9275110 100644
--- a/port/page.c
+++ b/port/page.c
@@ -250,11 +250,9 @@ duppage(Page *p)				/* Always call with p locked */
 	Page *np;
 	int color;
 
-	/* No dup for swap pages */
-	if(p->image == &swapimage) {
-		uncachepage(p);	
+	/* No dup for swap/cache pages */
+	if(p->image->notext)
 		return;
-	}
 
 	lock(&palloc);
 	/* No freelist cache when memory is very low */
@@ -333,7 +331,7 @@ uncachepage(Page *p)			/* Always called with a locked page */
 {
 	Page **l, *f;
 
-	if(p->image == 0)
+	if(p->image == 0 || p->image->notext)
 		return;
 
 	lock(&palloc.hashlock);
diff --git a/port/portdat.h b/port/portdat.h
index a5569f7485d4c2d1c671852339dbddcb431170c0..17212e3a4e759d3d106609ffe92d83c74b0a2dad 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -315,6 +315,7 @@ struct Image
 	Segment *s;			/* TEXT segment for image if running */
 	Image	*hash;			/* Qid hash chains */
 	Image	*next;			/* Free list */
+	int	notext;			/* no file associated */
 };
 
 struct Pte
@@ -500,7 +501,9 @@ enum
 	NERR = 15,
 	NNOTE = 5,
 
-	Nrq	= 5,
+	Nrq		= 20,
+	PriNormal	= 10,
+	PriRoot		= 5,
 };
 
 struct Proc
diff --git a/port/portfns.h b/port/portfns.h
index 707ac655ffb6fe4b1eeb978c03504b81058b59a2..67eba9326721f1d425c5ea6c26b45364eefa710f 100644
--- a/port/portfns.h
+++ b/port/portfns.h
@@ -1,8 +1,8 @@
 void		addrootfile(char*, uchar*, ulong);
 void		alarmkproc(void*);
 Block*		allocb(int);
+int		anyhigher(void);
 int		anyready(void);
-int		anyready0(void);
 Image*		attachimage(int, Chan*, ulong, ulong);
 long		authcheck(Chan*, char*, int);
 void		authclose(Chan*);
diff --git a/port/proc.c b/port/proc.c
index e20447d5a0df5eb867c94519ea7310f839268de7..94d0c0791f3971dec33ccfb4213237832a9d6b35 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -23,6 +23,7 @@ struct
 
 
 int	nrdy;
+int	lastreadied;
 Schedq	runq[Nrq];
 
 char *statename[] =
@@ -107,9 +108,13 @@ anyready(void)
 }
 
 int
-anyready0(void)
+anyhigher(void)
 {
-	return runq->head != 0;
+	int x;
+
+	x = lastreadied;
+	lastreadied = Nrq;
+	return nrdy && x <= up->priority;
 }
 
 void
@@ -138,6 +143,8 @@ ready(Proc *p)
 	nrdy++;
 	p->readyticks = m->ticks;
 	p->state = Ready;
+	if(lastreadied > p->priority)
+		lastreadied = p->priority;
 	unlock(runq);
 	splx(s);
 }
diff --git a/port/segment.c b/port/segment.c
index 84d47e91ef2506b06be1a7fd1b6a5b663b6c1708..df3c8ccf08f0e6db39233a3a0735fe9b0626d0e3 100644
--- a/port/segment.c
+++ b/port/segment.c
@@ -274,7 +274,7 @@ imagereclaim(void)
 	lock(&palloc);
 	for(p = palloc.head; p; p = p->next) {
 		if(p->ref == 0 && p->image && canlock(p)) {
-			if(p->ref == 0 && p->image != &swapimage)
+			if(p->ref == 0)
 				uncachepage(p);
 			unlock(p);
 		}
@@ -289,7 +289,7 @@ putimage(Image *i)
 	Chan *c;
 	Image *f, **l;
 
-	if(i == &swapimage)
+	if(i->notext)
 		return;
 
 	lock(i);
diff --git a/port/swap.c b/port/swap.c
index cd8b3c004b38fe273b449f1a6c09aeb219442980..f3e798ea40f6e178e769420e678c12e6109c66fd 100644
--- a/port/swap.c
+++ b/port/swap.c
@@ -33,6 +33,8 @@ swapinit(void)
 	iolist = xalloc(Maxpages*sizeof(Page*));
 	if(swapalloc.swmap == 0 || iolist == 0)
 		panic("swapinit: not enough memory");
+
+	swapimage.notext = 1;
 }
 
 ulong
diff --git a/port/sysproc.c b/port/sysproc.c
index 5efec57f7e46080f376a078d232ad737168cd62f..cd824976af0d02d3329f5b20cf2f87317560e724 100644
--- a/port/sysproc.c
+++ b/port/sysproc.c
@@ -397,9 +397,9 @@ sysexec(ulong *arg)
 	 *  '/' processes are high priority (hack to make /ip more responsive)
 	 */
 	if(devchar[tc->type] == L'/')
-		up->basepri = 0;
+		up->basepri = PriRoot;
 	else
-		up->basepri = 1;
+		up->basepri = PriNormal;
 	up->priority = up->basepri;
 	poperror();
 	close(tc);