x86: e820: user-defined memory maps: remove the range instead of update it to reserved

also let mem= to print out modified e820 map too

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/e820.c

@@ -1165,6 +1165,8 @@ static void early_panic(char *msg)
 	panic(msg);
 }
 
+static int userdef __initdata;
+
 /* "mem=nopentium" disables the 4MB page tables. */
 static int __init parse_memopt(char *p)
 {
@@ -1180,17 +1182,15 @@ static int __init parse_memopt(char *p)
 	}
 #endif
 
+	userdef = 1;
 	mem_size = memparse(p, &p);
 	end_user_pfn = mem_size>>PAGE_SHIFT;
-	e820_update_range(mem_size, ULLONG_MAX - mem_size,
-		E820_RAM, E820_RESERVED);
+	e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
 
 	return 0;
 }
 early_param("mem", parse_memopt);
 
-static int userdef __initdata;
-
 static int __init parse_memmap_opt(char *p)
 {
 	char *oldp;
@@ -1230,8 +1230,7 @@ static int __init parse_memmap_opt(char *p)
 		e820_add_region(start_at, mem_size, E820_RESERVED);
 	} else {
 		end_user_pfn = (mem_size >> PAGE_SHIFT);
-		e820_update_range(mem_size, ULLONG_MAX - mem_size,
-			E820_RAM, E820_RESERVED);
+		e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
 	}
 	return *p == '\0' ? 0 : -EINVAL;
 }