Sabre lite kernel issue(s)

[dubravkomoravsk]

Hello,

We've bought a Sabre Lite reference board from Element 14, containing an i.MX6 quad CPU. The board powers up and works correctly with preinstalled files. I've downloaded their recommended source files for u-boot, kernel and file system; compiled them according to instructions and flashed the board. u-boot works, but kernel doesn't show any signs of life.

I've tried changing serial console port, enabling early printks, printascii, attaching a terminal to both serial ports, attaching a monitor to hdmi output. It seems that after u-boot prints out "Starting kernel..." nothing at all happens.

u-boot version is 2009.08; kernel version is 3.14.28.

Any hints what else I could try?

I've found address of __log_buf where supposedly some printk outputs might be found in System.map, but it's a virtual address - how can I find out what is the corresponding physical address to I could check out the contents from boot?

Thanks in advance for all comments and suggestions.

I wrote a similar post on element 14's forum, but got no replies so far.

[gary_bisson]

Hi,

First of all, please update your U-Boot, using the 3.14.28 kernel requires U-Boot v2015.07 for display detection to work properly:

https://boundarydevices.com/compiling-latest-u-boot-for-i-mx6-2015-edition/

Then could you answer the following questions:

1- How are you building your kernel? Manually or using Buildroot or Yocto?

2- What revision exactly has been built?

3- What is the serial output when you try to boot? (please copy to pastebin)

Regards,

Gary

[dubravkomoravsk]

Thank you, I've built (manually) and flashed u-boot 2015.07, it worked (after adjusting mfgtool configuration a bit). Then I've downloaded and built Jethro release of Yocto following instructions from BoundaryDevices. After adjusting mfgtool to flash it since I don't have an SD card reader in desktop PC, the kernel loaded fine and everything works. :-)

Shall anyone else need it, the following line in ucl.xml essentially formats the SD card, initializes two partitions for kernel and file system and copies all the files:

  <CMD type="push" body="pipe gzip -d -c | dd of=/dev/mmcblk0 conv=notrunc,fsync bs=1M" file="files/boundary-eval-image-nitrogen6x.rootfs.sdcard.gz">Sending and writting rootfs</CMD>

All other lines related to that functionality shall be removed/commented out.