grub2: fix a few minor issues in help text

The help text of grub2 explains the detailed steps to create a disk
image with grub2 installed on it. However, the steps for the
BIOS-based systems have a few minor issues fixed by this patch:

 - When calling partx to get the partitions detected, we should do it
   on the /dev/loop0 block device, and not on the underlying disk.img
   image file.
 - The grub-bios-setup utility must be called as root to work properly
   on /dev/loop0.
 - The steps to cleanup the partx and loop device were missing.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

diff --git a/boot/grub2/Config.in b/boot/grub2/Config.in
index 5e7ccd2bfbe62d4a588fd28e2f1802c143ac3c0b..a27c07ab7a380b4c8e01ef37097a7e0d0ec4a204 100644 (file)
--- a/boot/grub2/Config.in
+++ b/boot/grub2/Config.in
@@ -24,17 +24,20 @@ config BR2_TARGET_GRUB2
                store Grub2. Leaving 1 MB of free space is safe.
          3. Setup loop device and loop partitions
             sudo losetup -f disk.img
-            sudo partx -a disk.img
+            sudo partx -a /dev/loop0
          4. Prepare the root partition
             sudo mkfs.ext3 -L root /dev/loop0p1
             sudo mount /dev/loop0p1 /mnt
             sudo tar -C /mnt -xf output/images/rootfs.tar
             sudo umount /mnt
          5. Install Grub2
-            ./output/host/usr/sbin/grub-bios-setup \
+            sudo ./output/host/usr/sbin/grub-bios-setup \
                        -b ./output/host/usr/lib/grub/i386-pc/boot.img \
                        -c ./output/images/grub.img -d . /dev/loop0
-         6. Your disk.img is ready!
+         6. Cleanup loop device
+            sudo partx -d /dev/loop0
+            sudo losetup -d /dev/loop0
+         7. Your disk.img is ready!
 
          To test your BIOS image in Qemu: