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Date: Mon, 20 Jun 2005 17:26:49 +0200
From: Jilles Tjoelker <jilles@stack.nl>
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Subject: what(1) on kernel binary
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On FreeBSD 4.x, one could easily determine the version and compilation
date of a kernel binary like this:

jilles@toad /home/jilles% what /kernel
/kernel:
        FreeBSD 4.11-STABLE #20: Mon May  9 18:43:52 CEST 2005

On FreeBSD 5.x/6.x with GCC 3.x, this doesn't work anymore.

The cause is that these two arrays (in /sys/conf/newvers.sh) are now both
aligned to a 32-byte boundary, so there are 28 null bytes between @(#)
and the version number:

char sccspad[32 - 4 /* sizeof(sccs) */] = { '\\0' };
char sccs[4] = { '@', '(', '#', ')' };

A possible solution is to change the two arrays to a single one
containing 28 null bytes and @(#).

char sccs[32] = { '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0',
'\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0',
'\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0',
'\\0', '@', '(', '#', ')' };

The symbols sccs and sccspad are not otherwise used in the RELENG_5
kernel.

what(1) still shows some garbage from the em(4) driver:
        $RCSfile: if_em_hw.h,v $$Revision: 1.41 $$Date: 2004/05/17 15:18:53 $
        $RCSfile: if_em_hw.h,v $$Revision: 1.41 $$Date: 2004/05/17 15:18:53 $

-- 
Jilles Tjoelker

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Content-Disposition: attachment; filename="newvers.sh.patch"

--- src/sys/conf/newvers.sh.orig	Thu Nov  4 23:02:55 2004
+++ src/sys/conf/newvers.sh	Wed Jun 15 18:15:55 2005
@@ -85,8 +85,7 @@
 i=`${MAKE:-make} -V KERN_IDENT`
 cat << EOF > vers.c
 $COPYRIGHT
-char sccspad[32 - 4 /* sizeof(sccs) */] = { '\\0' };
-char sccs[4] = { '@', '(', '#', ')' };
+char sccs[32] = { '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '\\0', '@', '(', '#', ')' };
 char version[] = "${VERSION} #${v}: ${t}\\n    ${u}@${h}:${d}\\n";
 char ostype[] = "${TYPE}";
 char osrelease[] = "${RELEASE}";

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