1) New "vm_page_alloc_contig" routine by me.

2) Created a new vm_page flag "PG_FREE" to help track free pages.
3) Use PG_FREE flag to detect inconsistencies in a few places.

3 files changed, 83 insertions, 5 deletions

diff --git a/sys/vm/vm_extern.h b/sys/vm/vm_extern.h
index d9e807d..eb16dae 100644
--- a/sys/vm/vm_extern.h
+++ b/sys/vm/vm_extern.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)vm_extern.h	8.2 (Berkeley) 1/12/94
- * $Id: vm_extern.h,v 1.4 1994/08/21 07:19:44 paul Exp $
+ * $Id: vm_extern.h,v 1.5 1994/09/02 15:06:50 davidg Exp $
  */
 
 #ifndef _VM_VM_EXTERN_H_
@@ -123,6 +123,7 @@ void		 vm_init_limits __P((struct proc *));
 void		 vm_mem_init __P((void));
 int		 vm_mmap __P((vm_map_t, vm_offset_t *, vm_size_t,
 		    vm_prot_t, vm_prot_t, int, caddr_t, vm_offset_t));
+vm_offset_t	 vm_page_alloc_contig __P((vm_offset_t, vm_offset_t, vm_offset_t, vm_offset_t));
 int		 vm_protect __P((vm_map_t,
 		    vm_offset_t, vm_size_t, boolean_t, vm_prot_t));
 void		 vm_set_page_size __P((void));
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index bce746b..5be3d61 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vm_page.c	7.4 (Berkeley) 5/7/91
- *	$Id: vm_page.c,v 1.4 1994/08/07 13:10:41 davidg Exp $
+ *	$Id: vm_page.c,v 1.5 1994/08/10 03:09:37 davidg Exp $
  */
 
 /*
@@ -320,7 +320,7 @@ vm_page_startup(starta, enda, vaddr)
 			++cnt.v_page_count;
 			++cnt.v_free_count;
 			m = PHYS_TO_VM_PAGE(pa);
-			m->flags = 0;
+			m->flags = PG_CLEAN | PG_FREE;
 			m->object = 0;
 			m->phys_addr = pa;
 			m->hold_count = 0;
@@ -584,6 +584,75 @@ vm_page_alloc(object, offset)
 	return(mem);
 }
 
+vm_offset_t
+vm_page_alloc_contig(size, low, high, alignment)
+	vm_offset_t	size;
+	vm_offset_t	low;
+	vm_offset_t	high;
+	vm_offset_t	alignment;
+{
+	int i, s, start = 0;
+	vm_offset_t addr, phys;
+	vm_page_t *pga = (vm_page_t *)vm_page_array;
+	extern vm_map_t kernel_map;
+
+	if ((alignment & (alignment - 1)) != 0)
+		panic("vm_page_alloc_contig: alignment must be a power of 2");
+
+	s = splhigh();
+again:
+	/*
+	 * Find first page in array that is free, within range, and aligned.
+	 */
+	for (i = start; i < cnt.v_page_count; i++) {
+		phys = VM_PAGE_TO_PHYS(pga[i]);
+		if ((pga[i]->flags & PG_FREE == PG_FREE) &&
+		    (phys >= low) && (phys < high) &&
+		    ((phys & (alignment - 1)) == 0))
+			break;
+	}
+
+	/*
+	 * If the above failed or we will exceed the upper bound, fail.
+	 */
+	if ((i == cnt.v_page_count) || ((VM_PAGE_TO_PHYS(pga[i]) + size) > high)) {
+		splx(s);
+		return (NULL);
+	}
+
+	start = i;
+
+	/*
+	 * Check successive pages for contiguous and free.
+	 */
+	for (i = start + 1; i < (start + size / PAGE_SIZE); i++) {
+		if ((VM_PAGE_TO_PHYS(pga[i]) !=
+		    (VM_PAGE_TO_PHYS(pga[i - 1]) + PAGE_SIZE)) ||
+		    ((pga[i]->flags & PG_FREE) != PG_FREE)) {
+			start++;
+			goto again;
+		}
+	}
+
+	/*
+	 * We've found a contiguous chunk that meets are requirements.
+	 * Allocate kernel VM, unfree and assign the physical pages to it
+	 * and return kernel VM pointer.
+	 */
+	addr = kmem_alloc_pageable(kernel_map, size);
+
+	for (i = start; i < (start + size / PAGE_SIZE); i++) {
+		TAILQ_REMOVE(&vm_page_queue_free, pga[i], pageq);
+		cnt.v_free_count--;
+		vm_page_wire(pga[i]);
+		pga[i]->flags = PG_CLEAN; /* shut off PG_FREE and any other flags */
+	}
+	pmap_qenter(addr, &pga[start], size / PAGE_SIZE);
+	
+	splx(s);
+	return (addr);
+}
+
 /*
  *	vm_page_free:
  *
@@ -609,14 +678,22 @@ void vm_page_free(mem)
 		mem->flags &= ~PG_INACTIVE;
 		cnt.v_inactive_count--;
 	}
+	if (mem->flags & PG_FREE)
+		panic("vm_page_free: freeing free page");
 
 	if (!(mem->flags & PG_FICTITIOUS)) {
 
 		simple_lock(&vm_page_queue_free_lock);
 		if (mem->wire_count) {
+			if (mem->wire_count > 1) {
+				printf("vm_page_free: wire count > 1 (%d)", mem->wire_count);
+				panic("vm_page_free: invalid wire count");
+			}
 			cnt.v_wire_count--;
 			mem->wire_count = 0;
 		}
+
+		mem->flags |= PG_FREE;
 		TAILQ_INSERT_TAIL(&vm_page_queue_free, mem, pageq);
 
 		cnt.v_free_count++;
diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index ee049aa..cbfb74c 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_page.h,v 1.4 1994/08/04 03:06:45 davidg Exp $
+ * $Id: vm_page.h,v 1.5 1994/09/06 11:28:44 davidg Exp $
  */
 
 /*
@@ -135,7 +135,7 @@ struct vm_page {
 #define	PG_DIRTY	0x0800		/* client flag to set when dirty */
 #define PG_REFERENCED	0x1000		/* page has been referenced */
 #define	PG_PAGEROWNED	0x4000		/* DEBUG: async paging op in progress */
-#define	PG_PTPAGE	0x8000		/* DEBUG: is a user page table page */
+#define	PG_FREE		0x8000		/* page is in free list */
 
 #if	VM_PAGE_DEBUG
 #define	VM_PAGE_CHECK(mem) { \