Re: [PATCH] Create floppy emulation boot CD with grub-mkimage

[Christian Franke]

Robert Millan wrote:
> On Sun, Feb 10, 2008 at 02:43:40PM +0100, Christian Franke wrote:
>   
> > This results in 6 possible image variants:
> >
> > 1. Floppy:                 --image-type=floppy
> > 2. CD, no emulation:       --image-type=cdrom [--emulation=none]
> > 3. CD, floppy emulation:   --image-type=cdrom --emulation=floppy
> > 4. CD, hdd emulation:      --image-type=cdrom --emulation=hdd
> > 5. USB without partitions: --image-type=superfloppy
> > 6. USB with partitions:    --image-type=hdd
> >
> > It may be possible to use the image #1 as image #5.
> >     
>
> I don't think it is really practical to support USB drives in grub-mkrescue.
> You'd have to require root permissions, which IMO beats the point of having
> a separate script from grub-install in first place.
>
>   

It may be useful to create small rescue images which can be later put on 
USB key with dd.
(BTW: The "floppy" image actually boots from USB at least on one of my 
PC. It appears as hd0).

Here a new patch, it uses the --emulation=floppy syntax from above.

My recent tests (see "[PATCH] Ensure boot CD can be accessed") show that 
direct CD boot might always not work.

The patch also adds a --joliet option, useful to access the long file 
names on Windows (which has no RR support).

Christian

2008-02-15  Christian Franke  <address@hidden>

        * util/i386/pc/grub-mkrescue.in: Add --emulation=floppy
        to create a floppy emulation boot CD when non emulation mode
        does not work.
        Add --joliet to enable Joliet cdrom filesystem extension.


--- grub2.orig/util/i386/pc/grub-mkrescue.in    2008-02-09 14:02:56.057039500 
+0100
+++ grub2/util/i386/pc/grub-mkrescue.in 2008-02-15 23:09:26.843750000 +0100
@@ -46,6 +46,8 @@ Make GRUB rescue image.
   --pkglibdir=DIR         use images from directory DIR instead of ${pkglibdir}
   --grub-mkimage=FILE     use FILE as grub-mkimage
   --image-type=TYPE       select floppy or cdrom (default)
+  --emulation=TYPE        select boot emulation type floppy, or none (default)
+  --joliet                enable Joliet filesystem extension (cdrom only)
 
 grub-mkimage generates a bootable rescue image of the specified type.
 
@@ -56,6 +58,8 @@ EOF
 image_type=cdrom
 input_dir=${pkglibdir}
 grub_mkimage=grub-mkimage
+emulation=none
+joliet=
 
 # Check the arguments.
 for option in "$@"; do
@@ -82,6 +86,16 @@ for option in "$@"; do
             echo "Unknown image type \`$image_type'" 1>&2
             exit 1 ;;
         esac ;;
+    --emulation=*)
+       emulation=`echo "$option" | sed 's/--emulation=//'`
+        case "$emulation" in
+          floppy|none) ;;
+          *)
+            echo "Unknown emulation type \`$emulation'" 1>&2
+            exit 1 ;;
+        esac ;;
+    --joliet)
+       joliet="-J" ;;
     -*)
        echo "Unrecognized option \`$option'" 1>&2
        usage
@@ -113,7 +127,7 @@ if test "x$overlay" = x ; then : ; else
   cp -dpR ${overlay}/* ${aux_dir}/
 fi
 
-if [ "x${image_type}" = "xfloppy" ] ; then
+if [ "x${image_type}" = xfloppy -o "x${emulation}" = xfloppy ] ; then
   # build memdisk
   memdisk_img=`mktemp`
   tar -C ${aux_dir} -cf ${memdisk_img} boot
@@ -125,8 +139,21 @@ if [ "x${image_type}" = "xfloppy" ] ; th
   rm -f ${memdisk_img}
 
   # build floppy image
-  cat ${input_dir}/boot.img ${core_img} /dev/zero | dd bs=1024 count=1440 > 
$output_image
+  if [ "x${image_type}" = xcdrom ] ; then
+    floppy_dir=`mktemp -d`
+    floppy_img=${floppy_dir}/grub_floppy.img
+  else
+    floppy_img=${output_image}
+  fi
+  cat ${input_dir}/boot.img ${core_img} /dev/zero | dd bs=1024 count=1440 > 
${floppy_img}
   rm -f ${core_img}
+
+  if [ "x${image_type}" = xcdrom ] ; then
+    # build iso image
+    genisoimage -b grub_floppy.img \
+      -o ${output_image} -r ${joliet} ${floppy_dir}
+    rm -rf ${floppy_dir}
+  fi
 else
   # build core.img
   core_img=`mktemp`
@@ -139,7 +166,7 @@ else
   # build iso image
   genisoimage -b boot/grub/grub_eltorito \
     -no-emul-boot -boot-load-size 4 -boot-info-table \
-    -o ${output_image} -r ${aux_dir}
+    -o ${output_image} -r ${joliet} ${aux_dir}
   rm -rf ${aux_dir}
 fi