Copying image from the SD to eMMC fails to boot

I have built a basic reference image for the BBB using Yocto/ Poky. It boots normally from the SD card. I then try to copy it over to the eMMC. My steps:

  1. Check the eMMC size with fdisk -l (get no of sectors and sector size): 7405568 sectors, 512 bytes wide sector.
  2. dd sc contents to the emmc: dd if=/dev/mmcblk0 of=/dev/mmcblk1 bs=512 count=7405568
  3. mount the boot partition on the emmc: mkdir /tmp/test && mount /dev/mmcblk1p1 /tmp/test
  4. edit the config: vi /tmp/test/extlinux/extlinux.conf. It looks like this:
default Yocto
label Yocto
   kernel /zImage
   fdtdir /
append root=/dev/mmcblk0p2 rootwait console=ttyS0,115200

I change the root dev from /dev/mmcblk0p2 to /dev/mmcblk1p2 (SD → emmc).

  1. After reboot. I only get “#####”, don’t even see the u-boot SPL output.

SD card boot log that works: BBB SD boot log yocto Kirkstone -

What am I missing? I would appreciate all help!