8GB eMMC flash?

Question

Hello Everyone, If there is an 8GB eMMC flash device on the MiniZed, why when I use the df command in PetaLinux does it only show 123M available? Thanks, Josh

mbrown · Accepted Answer

During production and test, we format only 128MB of eMMC to save time. You can use Linux fdisk utilities to create a larger partition. /Matt

stefanrousseau · Answer

Yes, the reason is that during production only 128M of the 8GB device is formatted to save time. You can format additional partitions (or delete the current one) with

fdisk /dev/mmcblk1

Note: One can create one huge extended partition, but that it will always be 7GB in size and you cannot format that as FAT32. And the largest primary partition size that you can create is 2048M (2GB).

Important note: After doing the fdisk, you should not do the formatting immediately, because the partition will not be available to format yet. You have to shut down and power cycle first! So after running fdisk (look at cat /usr/local/bin/format_emmc.sh to see how to do this in a script) you should shut down (shutdown -h now) and then power cycle by removing the power cable(s). Hitting the reset button is not enough. After reset you can run your format and then go through the reset again. Then you will see your formatted partition with df.

After making a 512MB partition:

root@plnx_arm:~# df

Filesystem Size Used Available Use% Mounted on

devtmpfs 64.0K 4.0K 60.0K 6% /dev

tmpfs 249.0M 28.0K 248.9M 0% /run

tmpfs 249.0M 44.0K 248.9M 0% /var/volatile

tmpfs 64.0K 4.0K 60.0K 6% /dev

/dev/mmcblk1p1 487.3M 4.0K 487.3M 0% /run/media/mmcblk1p1

stefanrousseau · Answer

On your MiniZed device, is there no file /usr/local/bin/format_emmc.sh ? If you are running a device from the factory or if you generated your running image from a published MiniZed BSP, it should be there. In the 2017.4 and 2018.2 BSP, the user scripts are stored under project-spec/meta-user/recipes-bsp/minized-misc/ Here is the file contentsfor the file (it only formats a 128MB partition): #Delete partition and add a new one of 128MB echo "fdisk /dev/mmcblk1 (1 partition of 128MB)" echo -e "d o n p 1 1 +128M w " | fdisk /dev/mmcblk1 echo "sleep 1" sleep 1 #Format as a DOS partition echo "mkdosfs -F 32 /dev/mmcblk1p1" mkdosfs -F 32 /dev/mmcblk1p1 echo "sleep 1" sleep 1 #Mount eMMC echo "/dev/mmcblk1p1 /mnt" mount /dev/mmcblk1p1 /mnt echo "ls -l /mnt" ls -l /mnt #Unmount drive again: echo "umount /mnt" umount /mnt Stefan

8GB eMMC flash?

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