--- linux-2.4.3-ac3/arch/i386/kernel/setup.c	Wed Apr  4 16:30:35 2001
+++ linux/arch/i386/kernel/setup.c	Wed Apr  4 16:34:03 2001
@@ -447,8 +447,8 @@
 /*
  * Sanitize the BIOS e820 map.
  *
- * Some e820 responses include overlapping entries.  The following 
- * replaces the original e820 map with a new one, removing overlaps.
+ * Some e820 responses include overlapping memory regions.  If overlaps are
+ * found, we'll replace the original e820 map with a new one (w/o overlaps).
  *
  */
 static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
@@ -464,14 +464,14 @@
 	struct change_member *change_tmp;
 	unsigned long current_type, last_type;
 	unsigned long long last_addr;
+	int overlap_entries, overlaps_found;
 	int chgidx, still_changing;
-	int overlap_entries;
 	int new_bios_entry;
 	int old_nr, new_nr;
 	int i;
 
 	/*
-		Visually we're performing the following (1,2,3,4 = memory types)...
+		Visually, we're performing the following (1,2,3,4 = mem types):
 
 		Sample memory map (w/overlaps):
 		   ____22__________________
@@ -517,7 +517,7 @@
 		if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr)
 			return -1;
 
-	/* create pointers for initial change-point information (for sorting) */
+	/* create pointers for initial change-point info (used for sorting) */
 	for (i=0; i < 2*old_nr; i++)
 		change_point[i] = &change_point_list[i];
 
@@ -535,13 +535,15 @@
 	while (still_changing)	{
 		still_changing = 0;
 		for (i=1; i < 2*old_nr; i++)  {
-			/* if <current_addr> > <last_addr>, swap */
-			/* or, if current=<start_addr> & last=<end_addr>, swap */
-			if ((change_point[i]->addr < change_point[i-1]->addr) ||
-				((change_point[i]->addr == change_point[i-1]->addr) &&
-				 (change_point[i]->addr == change_point[i]->pbios->addr) &&
-				 (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
-			   )
+			/* if <current_addr> < <last_addr>, swap */
+			/* or, if curr=<start_addr> & last=<end_addr>, swap */
+			if ((change_point[i]->addr<change_point[i-1]->addr) ||
+				((change_point[i]->addr ==
+					change_point[i-1]->addr) &&
+				 (change_point[i]->addr ==
+					change_point[i]->pbios->addr) &&
+				 (change_point[i-1]->addr !=
+					change_point[i-1]->pbios->addr)))
 			{
 				change_tmp = change_point[i];
 				change_point[i] = change_point[i-1];
@@ -552,47 +554,72 @@
 	}
 
 	/* create a new bios memory map, removing overlaps */
-	overlap_entries=0;	 /* number of entries in the overlap table */
-	new_bios_entry=0;	 /* index for creating new bios map entries */
-	last_type = 0;		 /* start with undefined memory type */
-	last_addr = 0;		 /* start with 0 as last starting address */
-	/* loop through change-points, determining affect on the new bios map */
+	overlaps_found=0;   /* indicates whether or not an overlap was found */
+	overlap_entries=0;  /* number of entries in the overlap table */
+	new_bios_entry=0;   /* index for creating new bios map entries */
+	last_type = 0;	    /* start with undefined memory type */
+	last_addr = 0;	    /* start with 0 as last starting address */
+	/* loop through change-points, determining affect on new bios map */
 	for (chgidx=0; chgidx < 2*old_nr; chgidx++)
 	{
 		/* keep track of all overlapping bios entries */
-		if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
+		if (change_point[chgidx]->addr ==
+			change_point[chgidx]->pbios->addr)
 		{
-			/* add map entry to overlap list (> 1 entry implies an overlap) */
-			overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
+			/* add entry to overlap list (>1 implies overlap) */
+			overlap_list[overlap_entries++]=
+				change_point[chgidx]->pbios;
+			/* check for legitimately overlapped memory regions */
+			if (overlap_entries == 2)
+			{
+				/* note: it's possible to have 2 entries w/out
+				   an overlap ([0]=end_addr, [1]=start_addr) */
+				if ((overlap_list[0]->addr +
+					overlap_list[0]->size) !=
+						(overlap_list[1]->addr))
+				{
+					overlaps_found = 1;
+				}
+			}
+			else if (overlap_entries > 1)
+			{
+				overlaps_found = 1;
+			}
 		}
 		else
 		{
-			/* remove entry from list (order independent, so swap with last) */
+			/* remove entry from list (order independent, so swap
+			   with last) */
 			for (i=0; i<overlap_entries; i++)
 			{
-				if (overlap_list[i] == change_point[chgidx]->pbios)
-					overlap_list[i] = overlap_list[overlap_entries-1];
+				if (overlap_list[i] ==
+					change_point[chgidx]->pbios)
+				{
+					overlap_list[i] =
+						overlap_list[overlap_entries-1];
+				}
 			}
 			overlap_entries--;
 		}
-		/* if there are overlapping entries, decide which "type" to use */
-		/* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
+		/* if overlapping entries, decide which "type" to use */
+		/* (larger takes precedence -- 1=usable, 2,3,4,4+=unusable) */
 		current_type = 0;
 		for (i=0; i<overlap_entries; i++)
 			if (overlap_list[i]->type > current_type)
 				current_type = overlap_list[i]->type;
-		/* continue building up new bios map based on this information */
+		/* continue building new bios map based on this information */
 		if (current_type != last_type)	{
 			if (last_type != 0)	 {
 				new_bios[new_bios_entry].size =
 					change_point[chgidx]->addr - last_addr;
-				/* move forward only if the new size was non-zero */
+				/* move forward if the new size is non-zero */
 				if (new_bios[new_bios_entry].size != 0)
 					if (++new_bios_entry >= E820MAX)
-						break; 	/* no more space left for new bios entries */
+						break;	/* no more space */
 			}
 			if (current_type != 0)	{
-				new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
+				new_bios[new_bios_entry].addr =
+					change_point[chgidx]->addr;
 				new_bios[new_bios_entry].type = current_type;
 				last_addr=change_point[chgidx]->addr;
 			}
@@ -601,9 +628,36 @@
 	}
 	new_nr = new_bios_entry;   /* retain count for new bios entries */
 
-	/* copy new bios mapping into original location */
-	memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
-	*pnr_map = new_nr;
+	/* if we found overlaps, replace bios map with an adjusted version */
+	if (overlaps_found == 1)
+	{
+		printk(KERN_INFO "Overlaps found in BIOS memory map:\n");
+		for (i = 0; i < old_nr; i++) {
+			printk(" BIOS-e820: %016Lx - %016Lx ", biosmap[i].addr,
+				biosmap[i].addr + biosmap[i].size);
+			switch (biosmap[i].type) {
+				case E820_RAM:
+					printk("(usable)\n");
+					break;
+				case E820_RESERVED:
+					printk("(reserved)\n");
+					break;
+				case E820_ACPI:
+					printk("(ACPI data)\n");
+					break;
+				case E820_NVS:
+					printk("(ACPI NVS)\n");
+					break;
+				default:
+					printk("type %lu\n", biosmap[i].type);
+					break;
+			}
+		}
+		printk(KERN_INFO "Compensating...\n");
+		/* copy new bios mapping into original location */
+		memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
+		*pnr_map = new_nr;
+	}
 
 	return 0;
 }