Yocto SD card boot, but no boot login on imx7ulp evk

[d-engineer]

We have built a yocto image for the imx7ulp evk as per the guide i.MX Yocto Project User's Guide (nxp.com) with the DISTRO as fsl-imx-fb, MACHINE as imx7ulpevk and built the core-image-minimal image.

Yocto generated the core-image-minimal file. We burnt this to an sd card using the command:

bzcat fsl-image-fb.wic.bz2 | sudo dd of=/dev/sdd bs=1M conv=fsync

When the SD card is loaded onto the imx7ulevk and booted, on the comm port connected to micro USB port, we get the u-boot messages followed by the kernel messages, but we never get a login prompt as the document says we should get.

Is there a missing step(s) to get the boot login?

When a display is connected on the HDMI port, only the yocto linux logo is visible with a blinking cursor. Attaching a USB keyboard and pressing any key does not seem to have any effect.


After failing with this for several days without any resolution we burn a new SD card with the imx-image-full-imx7ulpevk.wic image from the LF_v5.15.32-2.0.0_images_IMX7ULPEVK using the command:

sudo dd if=imx-image-full-imx7ulpevk.wic of=/dev/sdd bs=1M conv=fsync

But we get the same behaviour with this as well: u-Boot boots, kernel boots but does not provide a login prompt or any shell either on the comm port from the micro USB port or the HDMI.

The log from the micro USB comm port is attached for further investigation.

[AldoG · Accepted solution]

Hello,

Please note that on i.MX 7ULP EVK, the Arm Cortex-M4 image needs to be programmed. Otherwise, it will not boot. For i.MX 7ULP, to burn the Arm Cortext-M4 image to QuadSPI, perform the following steps:

1. Boot to the U-Boot console.

2. Probe the Quad SPI in U-Boot, and erase an enough big size QuardSPI flash space for this Arm Cortext-M4 image.
U-Boot > sf probe
U-Boot > sf erase 0x0 0x30000;

3. Read the Arm Cortext-M4 image (in the first vfat partition on the SD card demo image should have M4 example available) to memory address, the Arm Cortext-M4 image name is imx7ulp_m4_demo.img here.
U-Boot > fatload mmc 0:1 0x62000000 imx7ulp_m4_demo.img;

4. Write the Arm Cortext-M4 image to the QuardSPI.
U-Boot > sf write 0x62000000 0x0 0x30000

After this is done, reboot your board and it should boot correctly.

Best regards,
Aldo.

[d-engineer]

Thanks, that worked.

Is this documented anywhere in the imx7ulp docs?

[AldoG]

Hi,

Glad to hear that it worked, it is mentioned at the Linux Users, the same statemente.
And in the getting started it is expected to flash using UUU tool which already handles this.

Best regards,
Aldo.