Trying to boot from disk image with grub2

Question

I installed Ubuntu and while fresh, captured the whole drive with the command

sudo dd if=/dev/sda of=/dev/sdb/image.img

then placed it into

/boot/images/image.img

I want GRUB2 to boot from this image, as Windows does with "native boot" technology from VHDX. I copied memdisk into /boot with

cp /usr/lib/syslinux/memdisk /boot/

And created the new file 50_memdisk

/etc/grub.d/50_memdisk

with this content:

#!/bin/sh 
set -e IMAGES=/boot/images .
/usr/lib/grub/grub-mkconfig_lib 
if test -e /boot/memdisk ; then 
  MEMDISKPATH=$( make_system_path_relative_to_its_root "/boot/memdisk" )
  echo "Found memdisk: $MEMDISKPATH" >&2  find $IMAGES -name "*.img" | sort | while read image; 
  do 
    IMAGEPATH=$( make_system_path_relative_to_its_root "$image" )  
    echo "Found floppy image: $IMAGEPATH" >&2  
    cat << EOF menuentry "Bootable floppy: $(basename $IMAGEPATH | sed s/.img//)" 
    { EOF 
      prepare_grub_to_access_device ${GRUB_DEVICE_BOOT} | sed -e "s/^/\t/" 
      cat << EOF  linux16 $MEMDISKPATH bigraw  initrd16 $IMAGEPATH 
    } EOF 
  done 
fi

Then I ran

chmod +x /etc/grub.d/50_memdisk && update-grub

But GRUB2 shows while the boot process is returning

out of memory

What did I do wrong?

Answer 1

The image you generated is too big to fit in RAM so a ramdisk is not viable.