K26 SOM with Custom Carrier booting from emmc, SD card & USB

K26 SOM booting from SD card, USB and eMMC

This is Part-II tutorial on K26 SoM programming.

Part I tutorial is here: https://www.hackster.io/LogicTronix/k26-custom-carrier-programming-with-sd-emmc-and-petalinux

Note:

For making SD card as default boot as in KV260 Carrier board, one has to update the bootargs in petalinux project pointing to SD card device as shown in the following petalinux project configurations:

After configuring the petalinux project, build the project and generate the BOOT.BIN. Update the BOOT.BIN in qspi using xsct method as mentioned in the previous tutorial.

Lets Start:

In previous tutorial, EMMC partition was empty which makes secondary boot from SD card possible. But once EMMC is loaded with root filesystem, it will be not allow to boot from any other peripheral devices.

Follow these Steps after updating the BOOT.BIN to QSPI from K26 SOM base BSP. This will run the bootloader at the start and in default, load rootfs from EMMC.

After loading EMMC with rootfs one can boot from EMMC by default.

We are following KR260 carrier card for this tutorial but this tutorial flow will work for any custom carrier having USB, SD and eMMC (K26 already have eMMC).

Booting from SD card:

First create the SD card by loading the petalinux-sdimage.wic image using SD card burning tool like Balena Etcher.

Insert the SD card into carrier card containing K26 SOM. Connect the USB serial cable to carrier card and start the board. This will output the console to serial console in Host machine.

Stop the boot by pressing any key in the K26 SOM serial console.

Updated bootargs in Uboot console with following :

ZynqMP> setenv bootargs "earlycon   console=ttyPS0,115200 clk_ignore_unused ext4=/dev/sda2:/rootfs rw   rootwait"

Then start the boot by running boot command.

ZynqMP> boot

This will start the boot and load the rootfs from SD card.

One can verify the current running root filesystem by logging in the console and viewing the current filesystem using df -h command.

In the above filesystem list, /dev/sda2 corresponds to root filesystem stored in SD card.

Booting from USB:

First prepare the USB device (Pendrive or USB stick) with root filesystem partition by burning the petalinux-sdimage.wic image into USB storage device using burning tool like Balena Etcher.

Next attach the USB storage device to USB port of the K26 SOM carrier card.

Now, connect the necessary USB to serial cables and power to the K26 SOM board and power on the board.

Stop the boot by pressing any key in the K26 SOM serial console.

Updated bootargs in Uboot console with following :

ZynqMP> setenv bootargs "earlycon   console=ttyPS0,115200 clk_ignore_unused ext4=/dev/sdb2:/rootfs rw   rootwait"

Then start the boot by running boot command.

ZynqMP> boot

This will start the boot and load the rootfs from SD card.

One can verify the current root filesystem by running df command:

Here /dev/sdb2 stored the root filesystem present in USB device.

Expanding eMMC root filesystem

Reference for this eMMC booting is zuboard-boot-linux-from-emmc-5d9447

Default partition of EMMC with base wic image

It is showing root filesystem in EMMC partiotion of size 3.8 GB

Commands for expanding EMMC filesystem:

• First boot the board from SD card. This will allow to mount and unmount the EMMC filesystem
• Next run following commands to expand emmc filesystem. In this case we are expanding `/dev/mmcblck0p2` consisting root filesystem

# umount /dev/mmcblk0*   
# parted   /dev/mmcblk0 resizepart 2 100%   
# e2fsck -f   /dev/mmcblk0p2   
# resize2fs   /dev/mmcblk0p2

Now reboot the system to view the changes made in the filesystem

It is showing root filesystem in EMMC partition of size 13 GB.

This tutorial ends here!

Thanks for going through this tutorial!

Kudos to our Senior Engineer, Sanam Shakya for creating this custom carrier flow based tutorial series for Kria K26 SoMs.

For any queries or Kria K26 Custom Carrier development, FPGA design and ML Acceleration you can contact us at info@logictronix.com

LogicTronix is AMD-Xilinx partner for FPGA Design and ML Acceleration and also the partner for Kria SoMs for ML Acceleration!