From b58ff8f523fa9cf69f66c5476c4ac87ae8f20a43 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 10 Dec 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-12-10

---
 pc/devastar.c  |  3 ++
 pc/devi82365.c |  4 ++-
 pc/ether8003.c |  3 ++
 pc/fns.h       |  3 +-
 pc/main.c      | 37 +++++++++++++++++++-
 pc/mmu.c       | 95 ++++++++++++++++++++++++++++++++++++++++----------
 6 files changed, 123 insertions(+), 22 deletions(-)

diff --git a/pc/devastar.c b/pc/devastar.c
index 5121f26c902f23359e65fa3234ccd32c1f9c2d2c..7300d43988bef9d9ec7af0e5557e3a2b1538e848 100644
--- a/pc/devastar.c
+++ b/pc/devastar.c
@@ -417,6 +417,9 @@ astarreset(void)
 			a->irq = 15;
 		a->id = i;
 
+		if(isaget(a->mem, Pagesize, 0) == 0)
+			panic("astarreset: %lux", a->mem);
+
 		if(astarsetup(a) < 0){
 			xfree(a);
 			astar[nastar] = 0;
diff --git a/pc/devi82365.c b/pc/devi82365.c
index 5d26d29d4c07b3d261e2fa516b65def495dcb244..c0ee2d4062bc349871a16f025d855191569acf1e 100644
--- a/pc/devi82365.c
+++ b/pc/devi82365.c
@@ -316,7 +316,9 @@ getmap(Slot *pp, ulong offset, int attr)
 
 		/* grab ISA address space for memory maps */
 		for(i = 0; i < Nmap; i++)
-			pp->mmap[i].isa = isamem(Mchunk);
+			pp->mmap[i].isa = getisa(0, Mchunk, BY2PG);
+		if(pp->mmap[i].isa == 0)
+			panic("getmap");
 	}
 
 	/* look for a map that starts in the right place */
diff --git a/pc/ether8003.c b/pc/ether8003.c
index a8c85a0aadf82e483cb00c6e658dc206ca3286fe..b2c4d2c503a89bcdae5be47ed05f74dd28cdc5cb 100644
--- a/pc/ether8003.c
+++ b/pc/ether8003.c
@@ -190,6 +190,9 @@ reset(Ether *ether)
 	}
 	dp8390setea(ether);
 
+	if(getisa(ether->mem, ether->size, 0) == 0)
+		panic("ether8003: %lux reused", ether->mem);
+
 	return 0;
 }
 
diff --git a/pc/fns.h b/pc/fns.h
index f9dc1e3c3b7f898712e30b450a6303445c322750..32aaa0784c976360dd722b2ecb9214b1718fc54f 100644
--- a/pc/fns.h
+++ b/pc/fns.h
@@ -42,7 +42,8 @@ ulong	inl(int);
 void	insl(int, void*, int);
 int	iprint(char*, ...);
 int	isaconfig(char*, int, ISAConf*);
-ulong	isamem(int);
+ulong	getisa(ulong, int, int);
+void	putisa(ulong, int);
 void	kbdinit(void);
 long*	mapaddr(ulong);
 void	mathinit(void);
diff --git a/pc/main.c b/pc/main.c
index 7500b40ffdc146bdb8c18abd98a212faefd632a9..bc88dbee58f90a5322cdb4cde8b5507134ff984e 100644
--- a/pc/main.c
+++ b/pc/main.c
@@ -313,11 +313,37 @@ memclrtest(int meg, int len, long seed)
 		for(n = 0; n < BY2PG/BY2WD; n++)
 			if(lp[n] != ~(seed + (n^((BY2PG/BY2WD)-1))))
 				return -1;
-		memset(lp, '!', BY2PG);
+/*		memset(lp, '!', BY2PG);/**/
 	}
 	return 0;
 }
 
+/*
+ *  look for unused address space in 0xC8000 to 1 meg
+ */
+void
+romscan(void)
+{
+	uchar *p;
+
+	p = (uchar*)(KZERO+0xC8000);
+	while(p < (uchar*)(KZERO+0xE0000)){
+		p[0] = 0x55;
+		p[1] = 0xAA;
+		p[2] = 4;
+		if(p[0] != 0x55 || p[1] != 0xAA){
+			putisa(PADDR(p), 2048);
+			p += 2048;
+			continue;
+		}
+		p += p[2]*512;
+	}
+
+	p = (uchar*)(KZERO+0xE0000);
+	if(p[0] != 0x55 || p[1] != 0xAA)
+		putisa(PADDR(p), 64*1024);
+}
+
 void
 confinit(void)
 {
@@ -360,6 +386,7 @@ confinit(void)
 		nconf++;
 	}
 
+
 	/*
 	 *  size memory above 1 meg. Kernel sits at 1 meg.  We
 	 *  only recognize MB size chunks.
@@ -437,6 +464,14 @@ confinit(void)
 			break;
 		}
 
+	/*
+ 	 *  add address space holes holes under 16 meg to available
+	 *  isa space.
+	 */
+	romscan();
+	if(conf.topofmem < 16*MB)
+		putisa(conf.topofmem, 16*MB - conf.topofmem);
+
 	conf.npage = conf.npage0 + conf.npage1;
 	conf.ldepth = 0;
 	if(pcnt < 10)
diff --git a/pc/mmu.c b/pc/mmu.c
index d8aa14c8c25db164856b5f1876a3258243ee5086..80be42025d5469900dddb73be7609e2d2c1ce49e 100644
--- a/pc/mmu.c
+++ b/pc/mmu.c
@@ -88,12 +88,15 @@ static ulong	*kpt;		/* 2nd level page tables for kernel mem */
 #define MAXUMEG 64	/* maximum memory per user process in megabytes */
 #define ONEMEG (1024*1024)
 
+enum {
+	Nisa=	256,
+};
 struct
 {
 	Lock;
-	ulong addr; 	/* next available address for isa bus memory */
-	ulong end;	/* one past available isa bus memory */
-} isamemalloc;
+	ulong s[Nisa];
+	ulong e[Nisa];
+} isaalloc;
 
 /*
  *  Change current page table and the stack to use for exceptions
@@ -149,10 +152,8 @@ mmuinit(void)
 	ktoppg.va = (ulong)top;
 	ktoppg.pa = ktoppg.va & ~KZERO;
 
-	/*  map all memory to KZERO (add some address space for ISA memory) */
-	isamemalloc.addr = 0xd8000;
-	isamemalloc.end = 0xe0000;
-	npage = 64*MB/BY2PG;
+	/*  map all memory to KZERO */
+	npage = 128*MB/BY2PG;
 	nbytes = PGROUND(npage*BY2WD);		/* words of page map */
 	nkpt = nbytes/BY2PG;			/* pages of page map */
 	kpt = xspanalloc(nbytes, BY2PG, 0);
@@ -335,24 +336,80 @@ putmmu(ulong va, ulong pa, Page *pg)
 	splx(s);
 }
 
+/*
+ *  make isa address space available
+ */
+void
+putisa(ulong addr, int len)
+{
+	ulong e;
+	int i, hole;
+
+	addr &= ~KZERO;
+
+	e = addr + len;
+	lock(&isaalloc);
+	hole = -1;
+	for(i = 0; i < Nisa; i++){
+		if(isaalloc.s[i] == e){
+			isaalloc.s[i] = addr;
+			break;
+		}
+		if(isaalloc.e[i] == addr){
+			isaalloc.e[i] = e;
+			break;
+		}
+		if(isaalloc.s[i] == 0)
+			hole = i;
+	}
+	if(i >= Nisa && hole >= 0){
+		isaalloc.s[hole] = addr;
+		isaalloc.e[hole] = e;
+	}
+	unlock(&isaalloc);
+}
+
 /*
  *  allocate some address space (already mapped into the kernel)
  *  for ISA bus memory.
  */
 ulong
-isamem(int len)
+getisa(ulong addr, int len, int align)
 {
-	ulong a, x;
-
-	lock(&isamemalloc);
-	len = PGROUND(len);
-	x = isamemalloc.addr + len;
-	if(x > isamemalloc.end)
-		panic("isamem");
-	a = isamemalloc.addr;
-	isamemalloc.addr = x;
-	unlock(&isamemalloc);
-	return a;
+	int i;
+	ulong os, s, e;
+
+	lock(&isaalloc);
+	os = s = e = 0;
+	for(i = 0; i < Nisa; i++){
+		s = os = isaalloc.s[i];
+		if(s == 0)
+			continue;
+		e = isaalloc.e[i];
+		if(addr && addr >= s && addr < isaalloc.e[i])
+			break;
+		if(align > 0)
+			s = ((s + align - 1)/align)*align;
+		if(e - s >= len)
+			break;
+	}
+	if(i >= Nisa){
+		unlock(&isaalloc);
+		return 0;
+	}
+
+	/* remove */
+	isaalloc.s[i] = 0;
+	unlock(&isaalloc);
+
+	/* give back edges */
+	if(s != os)
+		putisa(os, s - os);
+	os = s + len;
+	if(os != e)
+		putisa(os, e - os);
+
+	return KZERO|s;
 }
 
 /*