svn commit: r232623 - head/sys/boot/i386/boot2

[John Baldwin]

Author: jhb
Date: Tue Mar  6 20:45:13 2012
New Revision: 232623
URL: http://svn.freebsd.org/changeset/base/232623

Log:
  Add a note to clarify why we create a relocated copy of boot1 in lower
  memory.

Modified:
  head/sys/boot/i386/boot2/boot1.S

Modified: head/sys/boot/i386/boot2/boot1.S
==============================================================================
--- head/sys/boot/i386/boot2/boot1.S	Tue Mar  6 20:37:06 2012	(r232622)
+++ head/sys/boot/i386/boot2/boot1.S	Tue Mar  6 20:45:13 2012	(r232623)
@@ -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