Reimport mbchk.

* util/Makefile.am: New file.
	* util/mbchk.c: Likewise.
	* Makefile.am (SUBDIRS): Add util.
	* configure.ac: New options --enable-mbchk. Check for HELP2MAN.
	(CFLAGS): Don't alter.
	(COND_MAN_PAGES): New conditional.
	(AC_CONFIG_FILES): Add util/Makefile.
	* doc/Makefile.am (kernel_CFLAGS): Add -m32 and -nostdlib.
	* doc/multiboot.texi (Invoking mbchk): New chapter.

doc/Makefile.am

@@ -10,7 +10,7 @@ pkginclude_HEADERS = multiboot.h
 if BUILD_EXAMPLE_KERNEL
 noinst_PROGRAMS = kernel
 kernel_SOURCES = $(EXAMPLES)
-kernel_CFLAGS = -fno-builtin -nostdinc -O -g -Wall \
+kernel_CFLAGS = -m32 -nostdlib -fno-builtin -nostdinc -O -g -Wall \
 	-imacros $(top_builddir)/config.h
 kernel_LDFLAGS = -nostdlib -Wl,-N -Wl,-Ttext -Wl,100000 -Wl,--build-id=none
 

doc/multiboot.texi

@@ -77,8 +77,9 @@ sequence standard. This edition documents version @value{VERSION}.
 * Terminology::                 
 * Specification::               
 * Examples::                    
-* History::                     
-* Index::                       
+* History::
+* Invoking mbchk::              How to use the Multiboot checker
+* Index::                  
 @end menu
 
 
@@ -1279,6 +1280,26 @@ Major changes plus HTMLification.
 @end itemize
 @end table
 
+@node Invoking mbchk
+@chapter Invoking mbchk
+
+The program @command{mbchk} checks for the format of a Multiboot
+kernel. We recommend using this program before booting your own kernel.
+
+@command{mbchk} accepts the following options:
+
+@table @option
+@item --help
+Print a summary of the command-line options and exit.
+
+@item --version
+Print the version number of GRUB and exit.
+
+@item --quiet
+Suppress all normal output.
+@end table
+
+
 
 @node Index
 @unnumbered Index