i.MX ProcessorsのトピックRe: Having trouble accessing linux console over UART

Having trouble accessing linux console over UART

jaux_al — Wed, 02 Dec 2020 18:24:18 GMT

I built a Linux image for iMX8 board, which was flashed to the SD card via the following commands:

bunzip2 -dk -f core-image-minimal-imx8qxpmek.sdcard.bz2 sudo dd if=core-image-minimal-imx8qxpmek.sdcard of=/dev/sdb bs=1M conv=fsync

But when I insert an SD card, and connect the microUSB to the debug port from the host machine, I don't really see anything coming up in a serial session.

I see 4 UART ports coming up so that's good, but I don't really see anything let alone a Linux console in a serial session in at least COM32 and ttyUSB0 on Linux

I checked the switches on the board and they're set to ON, ON, OFF, OFF for 1-4 bits as suggested in the manual.

Re: Having trouble accessing linux console over UART

joanxie — Fri, 04 Dec 2020 04:25:27 GMT

what version do you download to the board? did you download the images to the sd card successfully? how about using uuu tools to download images to the sd card?

Re: Having trouble accessing linux console over UART

jaux_al — Fri, 04 Dec 2020 05:13:05 GMT

Linux version? 4.14.98.

I was able to flash the image to the SD card. I didn't look much into if certain files exist in the SD card because I see a yocto-build image can be flashed directly without having to worry about setting up partitions and what not.

are you implying the issue is potentially with the flashing technique?

Isn't eMMC is required for uuu? SD card wouldn't work?

Also, given there are 4 ports, which port corresponds to which core? I see there are two different cores i.e cortex A and M. Core A runs linux and M freeRTOS?

Re: Having trouble accessing linux console over UART

joanxie — Fri, 11 Dec 2020 03:06:29 GMT

sd card can work, where did you get the minimal sdcard images? did you built it by yourself? I suggest that you can download the demo images to test first, you can download them from the link as below:

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applications-processors:IMXLINUX

Re: Having trouble accessing linux console over UART

jaux_al — Fri, 11 Dec 2020 04:03:34 GMT

I tried using one of the demo images into a new SD card which worked, but the same image file that I am generating from Yocto doesn't.

I built the image myself, via Yocto. Do you see what could be a possible reason for the board to not boot up properly?

Re: Having trouble accessing linux console over UART

joanxie — Mon, 14 Dec 2020 08:52:43 GMT

I never tested minimal images, how about building fsl-image-validation-imx or fsl-image-qt5-validation-imx? I have tested them successfully