1.1--- a/sys/src/9/port/devproc.c
     1.2+++ b/sys/src/9/port/devproc.c
     1.3@@ -134,7 +134,7 @@ Cmdtab proccmd[] = {
     1.4 };
     1.5 
     1.6 /* Segment type from portdat.h */
     1.7-static char *sname[]={ "Text", "Data", "Bss", "Stack", "Shared", "Phys", };
     1.8+static char *sname[]={ "Text", "Data", "Bss", "Stack", "Shared", "Phys", "Fixed", };
     1.9 
    1.10 /*
    1.11  * Qids are, in path:

     2.1--- a/sys/src/9/port/devsegment.c
     2.2+++ b/sys/src/9/port/devsegment.c
     2.3@@ -56,6 +56,7 @@ static	Segment* globalsegattach(Proc *p,
     2.4 static	int	cmddone(void*);
     2.5 static	void	segmentkproc(void*);
     2.6 static	void	docmd(Globalseg *g, int cmd);
     2.7+static	Segment* fixedseg(uintptr va, ulong len);
     2.8 
     2.9 /*
    2.10  *  returns with globalseg incref'd
    2.11@@ -98,7 +99,7 @@ segmentgen(Chan *c, char*, Dirtab*, int,
    2.12 {
    2.13 	Qid q;
    2.14 	Globalseg *g;
    2.15-	ulong size;
    2.16+	uintptr size;
    2.17 
    2.18 	switch(TYPE(c)) {
    2.19 	case Qtopdir:
    2.20@@ -328,7 +329,11 @@ segmentread(Chan *c, void *a, long n, vl
    2.21 		g = c->aux;
    2.22 		if(g->s == nil)
    2.23 			error("segment not yet allocated");
    2.24-		sprint(buf, "va %#lux %#lux\n", g->s->base, g->s->top-g->s->base);
    2.25+		if(g->s->type&SG_TYPE == SG_FIXED)
    2.26+			sprint(buf, "va %#p %#p fixed %#p\n", g->s->base, g->s->top-g->s->base,
    2.27+				g->s->map[0]->pages[0]->pa);
    2.28+		else
    2.29+			sprint(buf, "va %#p %#p\n", g->s->base, g->s->top-g->s->base);
    2.30 		return readstr(voff, a, n, buf);
    2.31 	case Qdata:
    2.32 		g = c->aux;
    2.33@@ -362,7 +367,7 @@ segmentwrite(Chan *c, void *a, long n, v
    2.34 {
    2.35 	Cmdbuf *cb;
    2.36 	Globalseg *g;
    2.37-	ulong va, len, top;
    2.38+	uintptr va, top, len;
    2.39 
    2.40 	if(c->qid.type == QTDIR)
    2.41 		error(Eperm);
    2.42@@ -376,14 +381,19 @@ segmentwrite(Chan *c, void *a, long n, v
    2.43 				error("already has a virtual address");
    2.44 			if(cb->nf < 3)
    2.45 				error(Ebadarg);
    2.46-			va = strtoul(cb->f[1], 0, 0);
    2.47-			len = strtoul(cb->f[2], 0, 0);
    2.48+			va = strtoull(cb->f[1], 0, 0);
    2.49+			len = strtoull(cb->f[2], 0, 0);
    2.50 			top = PGROUND(va + len);
    2.51 			va = va&~(BY2PG-1);
    2.52+			if(va == 0 || top > USTKTOP || top <= va)
    2.53+				error(Ebadarg);
    2.54 			len = (top - va) / BY2PG;
    2.55-			if(len == 0)
    2.56-				error(Ebadarg);
    2.57-			g->s = newseg(SG_SHARED, va, len);
    2.58+			if(cb->nf >= 4 && strcmp(cb->f[3], "fixed") == 0){
    2.59+				if(!iseve())
    2.60+					error(Eperm);
    2.61+				g->s = fixedseg(va, len);
    2.62+			} else
    2.63+				g->s = newseg(SG_SHARED, va, len);
    2.64 		} else
    2.65 			error(Ebadctl);
    2.66 		break;
    2.67@@ -561,6 +571,73 @@ segmentkproc(void *arg)
    2.68 	pexit("done", 1);
    2.69 }
    2.70 
    2.71+/*
    2.72+ * allocate a fixed segment with sequential run of of adjacent
    2.73+ * user memory pages.
    2.74+ */
    2.75+static Segment*
    2.76+fixedseg(uintptr va, ulong len)
    2.77+{
    2.78+	KMap *k;
    2.79+	Segment *s;
    2.80+	Page **f, *p;
    2.81+	ulong n, i, j;
    2.82+	int color;
    2.83+
    2.84+	s = newseg(SG_FIXED, va, len);
    2.85+	if(waserror()){
    2.86+		putseg(s);
    2.87+		nexterror();
    2.88+	}
    2.89+	lock(&palloc);
    2.90+	i = 0;
    2.91+	p = palloc.pages;
    2.92+	color = getpgcolor(va);
    2.93+	for(n = palloc.user; n >= len; n--, p++){
    2.94+		if(p->ref != 0 || i != 0 && (p[-1].pa+BY2PG) != p->pa || i == 0 && p->color != color){
    2.95+		Retry:
    2.96+			i = 0;
    2.97+			continue;
    2.98+		}
    2.99+		if(++i < len)
   2.100+			continue;
   2.101+		for(j = 0; j < i; j++, p--){
   2.102+			for(f = &palloc.head; *f != nil; f = &((*f)->next)){
   2.103+				if(*f == p){
   2.104+					*f = p->next;
   2.105+					goto Freed;
   2.106+				}
   2.107+			}
   2.108+			while(j-- > 0)
   2.109+				pagechainhead(++p);
   2.110+			goto Retry;
   2.111+		Freed:
   2.112+			palloc.freecount--;
   2.113+		}
   2.114+		unlock(&palloc);
   2.115+
   2.116+		while(i-- > 0){
   2.117+			p++;
   2.118+			p->ref = 1;
   2.119+			p->va = va;
   2.120+			p->modref = 0;
   2.121+			p->txtflush = ~0;
   2.122+			
   2.123+			k = kmap(p);
   2.124+			memset((void*)VA(k), 0, BY2PG);
   2.125+			kunmap(k);
   2.126+			
   2.127+			segpage(s, p);
   2.128+			va += BY2PG;
   2.129+		}
   2.130+		poperror();
   2.131+		return s;
   2.132+	}
   2.133+	unlock(&palloc);
   2.134+	error(Enomem);
   2.135+	return nil;
   2.136+}
   2.137+
   2.138 Dev segmentdevtab = {
   2.139 	'g',
   2.140 	"segment",

     3.1--- a/sys/src/9/port/fault.c
     3.2+++ b/sys/src/9/port/fault.c
     3.3@@ -267,6 +267,7 @@ fixfault(Segment *s, uintptr addr, int r
     3.4 			copypage(old, *pg);
     3.5 			putpage(old);
     3.6 		}
     3.7+	case SG_FIXED:			/* Never paged out */
     3.8 		mmuphys = PPN((*pg)->pa) | PTEWRITE | PTEVALID;
     3.9 		(*pg)->modref = PG_MOD|PG_REF;
    3.10 		break;

     4.1--- a/sys/src/9/port/portdat.h
     4.2+++ b/sys/src/9/port/portdat.h
     4.3@@ -341,6 +341,7 @@ enum
     4.4 	SG_STACK	= 03,
     4.5 	SG_SHARED	= 04,
     4.6 	SG_PHYSICAL	= 05,
     4.7+	SG_FIXED	= 06,
     4.8 
     4.9 	SG_RONLY	= 0040,		/* Segment is read only */
    4.10 	SG_CEXEC	= 0100,		/* Detach at exec */

     5.1--- a/sys/src/9/port/segment.c
     5.2+++ b/sys/src/9/port/segment.c
     5.3@@ -156,6 +156,7 @@ dupseg(Segment **seg, int segno, int sha
     5.4 	case SG_TEXT:		/* New segment shares pte set */
     5.5 	case SG_SHARED:
     5.6 	case SG_PHYSICAL:
     5.7+	case SG_FIXED:
     5.8 		goto sameseg;
     5.9 
    5.10 	case SG_STACK:
    5.11@@ -489,8 +490,11 @@ mfreeseg(Segment *s, uintptr start, ulon
    5.12 	if(pages == 0)
    5.13 		return;
    5.14 
    5.15-	if((s->type&SG_TYPE) == SG_PHYSICAL)
    5.16+	switch(s->type&SG_TYPE){
    5.17+	case SG_PHYSICAL:
    5.18+	case SG_FIXED:
    5.19 		return;
    5.20+	}
    5.21 
    5.22 	/*
    5.23 	 * we have to make sure other processors flush the

     6.1--- a/sys/src/9/port/sysproc.c
     6.2+++ b/sys/src/9/port/sysproc.c
     6.3@@ -751,6 +751,7 @@ syssegbrk(va_list list)
     6.4 		case SG_DATA:
     6.5 		case SG_STACK:
     6.6 		case SG_PHYSICAL:
     6.7+		case SG_FIXED:
     6.8 			error(Ebadarg);
     6.9 		default:
    6.10 			return (uintptr)ibrk(va_arg(list, uintptr), i);