Access to eMMC partition from SD with Debian

Hi to all,

I would use all IO pins on my BeagleBone Green card.

For this I boot from a SD card a Debian Linux distribution.

Now I should have access to eMMC memory and edit the /boot/uEnv.txt file.

I do:
mkdir /old
mount /dev/mmcblk0p1 /old

But now, in /old I find a copy of the SD partition and not the eMMC partition!

How can I fix the problem?