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Date:      Thu, 1 Mar 2001 16:25:17 +0000 (GMT)
From:      Doug Rabson <dfr@nlsystems.com>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        <ia64@FreeBSD.org>
Subject:   Re: Grrrr..
Message-ID:  <Pine.BSF.4.33.0103011622410.42199-100000@herring.nlsystems.com>
In-Reply-To: <XFMail.010227112837.jhb@FreeBSD.org>

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On Tue, 27 Feb 2001, John Baldwin wrote:

>
> On 27-Feb-01 Doug Rabson wrote:
> > I think it would be a good idea. Basically, we need to be able to cope
> > with the calls to pmap_map() which the VM system makes during
> > initialisation. I'm not sure exactly how many there are - perhaps we can
> > map them all using translation registers, which would be nice.
>
> That would be ideal, yes. :)  I guess I'll read up some more on the VM stuff in
> the ia64 docco and see if I can make some sense of it.

I remember now. I always intended to redo pmap_map() via the direct-mapped
segments. This saves kernel virtual address space (of which there is
plenty) but more importantly saves TLB entries and on ia64 VHTP entries. I
just hacked up this patch which isn't tested on anything but I think its
on the right lines. Beware of conflicts - Drew Gallatin is working in this
area.

Index: alpha/alpha/pmap.c
===================================================================
RCS file: /home/ncvs/src/sys/alpha/alpha/pmap.c,v
retrieving revision 1.51
diff -u -r1.51 pmap.c
--- alpha/alpha/pmap.c	2001/01/30 00:35:35	1.51
+++ alpha/alpha/pmap.c	2001/03/01 16:21:21
@@ -898,6 +898,24 @@
 	return (virt);
 }

+/*
+ *	Used to map a range of physical addresses into kernel
+ *	virtual address space.
+ *
+ *	The value passed in '*virt' is a suggested virtual address for
+ *	the mapping. Architectures which can support a direct-mapped
+ *	physical to virtual region can return the appropriate address
+ *	within that region, leaving '*virt' unchanged. Other
+ *	architectures should map the pages starting at '*virt' and
+ *	update '*virt' with the first usable address after the mapped
+ *	region.
+ */
+vm_offset_t
+pmap_map(vm_offset_t *virt, vm_offset_t start, vm_offset_t end, int prot)
+{
+	return ALPHA_PHYS_TO_K0SEG(start);
+}
+

 static vm_page_t
 pmap_page_lookup(vm_object_t object, vm_pindex_t pindex)
Index: i386/i386/pmap.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/i386/pmap.c,v
retrieving revision 1.272
diff -u -r1.272 pmap.c
--- i386/i386/pmap.c	2001/01/30 00:35:34	1.272
+++ i386/i386/pmap.c	2001/03/01 16:20:03
@@ -712,22 +712,30 @@
  *	Used to map a range of physical addresses into kernel
  *	virtual address space.
  *
- *	For now, VM is already on, we only need to map the
- *	specified memory.
+ *	The value passed in '*virt' is a suggested virtual address for
+ *	the mapping. Architectures which can support a direct-mapped
+ *	physical to virtual region can return the appropriate address
+ *	within that region, leaving '*virt' unchanged. Other
+ *	architectures should map the pages starting at '*virt' and
+ *	update '*virt' with the first usable address after the mapped
+ *	region.
  */
 vm_offset_t
 pmap_map(virt, start, end, prot)
-	vm_offset_t virt;
+	vm_offset_t *virt;
 	vm_offset_t start;
 	vm_offset_t end;
 	int prot;
 {
+	vm_offset_t sva = *virtp;
+	vm_offset_t va = sva;
 	while (start < end) {
-		pmap_kenter(virt, start);
-		virt += PAGE_SIZE;
+		pmap_kenter(va, start);
+		va += PAGE_SIZE;
 		start += PAGE_SIZE;
 	}
-	return (virt);
+	*virt = va;
+	return (sva);
 }


Index: ia64/ia64/pmap.c
===================================================================
RCS file: /home/ncvs/src/sys/ia64/ia64/pmap.c,v
retrieving revision 1.11
diff -u -r1.11 pmap.c
--- ia64/ia64/pmap.c	2001/01/21 22:23:10	1.11
+++ ia64/ia64/pmap.c	2001/03/01 16:21:13
@@ -1115,22 +1115,18 @@
  *	Used to map a range of physical addresses into kernel
  *	virtual address space.
  *
- *	For now, VM is already on, we only need to map the
- *	specified memory.
+ *	The value passed in '*virt' is a suggested virtual address for
+ *	the mapping. Architectures which can support a direct-mapped
+ *	physical to virtual region can return the appropriate address
+ *	within that region, leaving '*virt' unchanged. Other
+ *	architectures should map the pages starting at '*virt' and
+ *	update '*virt' with the first usable address after the mapped
+ *	region.
  */
 vm_offset_t
-pmap_map(vm_offset_t virt, vm_offset_t start, vm_offset_t end, int prot)
+pmap_map(vm_offset_t *virt, vm_offset_t start, vm_offset_t end, int prot)
 {
-	/*
-	 * XXX We should really try to use larger pagesizes here to
-	 * cut down the number of PVs used.
-	 */
-	while (start < end) {
-		pmap_kenter(virt, start);
-		virt += PAGE_SIZE;
-		start += PAGE_SIZE;
-	}
-	return (virt);
+	return IA64_PHYS_TO_RR7(start);
 }

 /*
Index: vm/pmap.h
===================================================================
RCS file: /home/ncvs/src/sys/vm/pmap.h,v
retrieving revision 1.37
diff -u -r1.37 pmap.h
--- vm/pmap.h	2000/10/17 10:05:49	1.37
+++ vm/pmap.h	2001/03/01 16:18:30
@@ -110,7 +110,7 @@
 boolean_t	 pmap_ts_referenced __P((vm_page_t m));
 void		 pmap_kenter __P((vm_offset_t va, vm_offset_t pa));
 void		 pmap_kremove __P((vm_offset_t));
-vm_offset_t	 pmap_map __P((vm_offset_t, vm_offset_t, vm_offset_t, int));
+vm_offset_t	 pmap_map __P((vm_offset_t *, vm_offset_t, vm_offset_t, int));
 void		 pmap_object_init_pt __P((pmap_t pmap, vm_offset_t addr,
 		    vm_object_t object, vm_pindex_t pindex, vm_offset_t size,
 		    int pagelimit));
Index: vm/vm_page.c
===================================================================
RCS file: /home/ncvs/src/sys/vm/vm_page.c,v
retrieving revision 1.156
diff -u -r1.156 vm_page.c
--- vm/vm_page.c	2000/12/26 19:41:38	1.156
+++ vm/vm_page.c	2001/03/01 16:17:39
@@ -242,8 +242,6 @@
 	 *
 	 * Note: This computation can be tweaked if desired.
 	 */
-	vm_page_buckets = (struct vm_page **)vaddr;
-	bucket = vm_page_buckets;
 	if (vm_page_bucket_count == 0) {
 		vm_page_bucket_count = 1;
 		while (vm_page_bucket_count < atop(total))
@@ -255,16 +253,16 @@
 	/*
 	 * Validate these addresses.
 	 */
-
 	new_start = start + vm_page_bucket_count * sizeof(struct vm_page *);
 	new_start = round_page(new_start);
-	mapped = round_page(vaddr);
-	vaddr = pmap_map(mapped, start, new_start,
+	mapped = pmap_map(&vaddr, start, new_start,
 	    VM_PROT_READ | VM_PROT_WRITE);
+	bzero((caddr_t) mapped, new_start - start);
 	start = new_start;
-	vaddr = round_page(vaddr);
-	bzero((caddr_t) mapped, vaddr - mapped);

+	vm_page_buckets = (struct vm_page **)mapped;
+	bucket = vm_page_buckets;
+
 	for (i = 0; i < vm_page_bucket_count; i++) {
 		*bucket = NULL;
 		bucket++;
@@ -275,7 +273,6 @@
 	 * use (taking into account the overhead of a page structure per
 	 * page).
 	 */
-
 	first_page = phys_avail[0] / PAGE_SIZE;

 	page_range = phys_avail[(nblocks - 1) * 2 + 1] / PAGE_SIZE - first_page;
@@ -286,16 +283,11 @@
 	 * Initialize the mem entry structures now, and put them in the free
 	 * queue.
 	 */
-	vm_page_array = (vm_page_t) vaddr;
-	mapped = vaddr;
-
-	/*
-	 * Validate these addresses.
-	 */
 	new_start = round_page(start + page_range * sizeof(struct vm_page));
-	mapped = pmap_map(mapped, start, new_start,
+	mapped = pmap_map(&vaddr, start, new_start,
 	    VM_PROT_READ | VM_PROT_WRITE);
 	start = new_start;
+	vm_page_array = (vm_page_t) mapped;

 	first_managed_page = start / PAGE_SIZE;


-- 
Doug Rabson				Mail:  dfr@nlsystems.com
					Phone: +44 20 8348 6160



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