Add a note to clarify why we create a relocated copy of boot1 in lower

memory.
2012-03-06 20:45:13 +00:00 · 2012-03-06 20:45:13 +00:00 · 8bf6dd98a7
commit 8bf6dd98a7
parent e13dfc355c
1 changed files with 4 additions and 1 deletions
--- a/sys/boot/i386/boot2/boot1.S
+++ b/sys/boot/i386/boot2/boot1.S
@ -125,7 +125,10 @@ main:		cld				# String ops inc
 		mov $start,%sp			#  stack
 /*
 * Relocate ourself to MEM_REL.  Since %cx == 0, the inc %ch sets
- * %cx == 0x100.
+ * %cx == 0x100.  Note that boot1 does not use this relocated copy
+ * of itself while loading boot2; however, BTX reclaims the memory
+ * used by boot1 during its initialization.  As a result, boot2 uses
+ * xread from the relocated copy.
 */
 		mov %sp,%si			# Source
 		mov $MEM_REL,%di		# Destination