Date: Tue, 6 Mar 2012 20:45:13 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r232623 - head/sys/boot/i386/boot2 Message-ID: <201203062045.q26KjDR8056867@svn.freebsd.org>
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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
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