Frequently Asked Questions / Common Debug Tips

This page documents common questions that developers may encounter while using Kria SOM.

Released Linux Images Not Booting

All AMD released images are verified on their supported Starter Kit. If an released image does not boot on the Starter Kit, for an example you may see errors like this while booting, for an example, Ubuntu:

[   17.644316] emc: device handler registered
[   17.658214] rdac: device handler registered
[   20.374057] tpm tpm0: A TPM error (256) occurred attempting the self test

It is usually because the Starter Kit needs an updated boot firmware. Download the correct version of boot firmware according to the wiki, and use [image recovery application](

Root Privileges

The ubuntu user does not have root privileges. Most commands used in tutorials must be run using sudo, and it may be prompted to enter your password.

For security, by default, the root user is disabled. If user want to login as root user, perform the following steps. Use the ubuntu user’s password on the first password prompt, then set a new password for the root user. User can now login as root user using the newly set root user password.

ubuntu@kria:\~\$ sudo -i
sudo\] password for ubuntu:

PPA Error Requiring Setting Timezone

If you receive a PPA error or no response when executing “apt update” command, it maybe due to wrong timezone/time on the system. The followings are commands to set System Timezone and locale:

  • Set timezone

sudo timedatectl set-ntp true
sudo timedatectl set-timezone America/Los_Angeles
  • Set locale

sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8
  • set the date and time.

sudo date --set "11 January 2023 16:47:00"

Docker Space Limitation

The storage volume on the SD card can be limited with multiple Docker images. If there are space issues, use the following command to remove the existing container.

sudo docker rmi --force $INSTALLED_DOCKER_IMAGE

Debug Monitors

Monitor should be connected properly to the board before power on, otherwise the resolution will not be recognized correctly.

Ensure to use certified cables for DP and HDMI, recommended specs are HDMI 2.0 and DP 1.2 above. If cables are faulty, they could cause distortions or disable display.

Modetest is a test tool which can be found as part of the libdrm suite of test tools.

Depending on if there is a video mixer in the PL or not, modetest would either directly test the DP, or go through video mixer using -D 80000000.v_mix argument.

Note that among examples using a monitor, AI Box and Defect Detect have video mixer; Smartcam and NLP SmartVision do not have video mixer.

Ensure status of monitor is connected

modetest -M xlnx [-D 80000000.v_mix]

The above command would read out the monitors EDID information.

id      encoder status          name            size (mm)       modes   encoders
52      51      connected       DP-1            610x350         43      51

Display modes supported by your display

modetest -M xlnx [-D 80000000.v_mix]

Below are the modes that are supported by your display.

        name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot)
  3840x2160 30.00 3840 4016 4104 4400 2160 2168 2178 2250 297000 flags: phsync, pvsync; type: driver
  3840x2160 30.00 3840 4016 4104 4400 2160 2168 2178 2250 297000 flags: phsync, pvsync; type: driver

Ensure display is capable of supporting user requested resolution and refresh rates to the application.

Current mode

modetest -M xlnx [-D 80000000.v_mix]

CRTC indicates the current mode that is set.

id      fb      pos     size
40      47      (0,0)   (3840x2160)
  3840x2160 30.00 3840 4016 4104 4400 2160 2168 2178 2250 297000 flags: phsync, pvsync; type: driver

Test to determine if display is OK

Example for 4k and video mixer::

modetest -M xlnx -D 80000000.v_mix -s 52@40:3840x2160@NV16

The above command sets a mode, blue screen appears on the display.

Blue Screen

Example for less resolution and without video mixer:

modetest -M xlnx -s 43:1024x768-60@AR24 modetest -M xlnx -s 43:1920x1080-60@AR24

The above command sets a mode, SMPTE Color Bars appears on the display.

SMPTE color bars


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