Debugging

Grabbing Logs

  • If you're experiencing a firmware problem, provide output from cbmem console.
    • If you're running Linux, the output from dmesg, and dmidecode can also be helpful
  • If you're experiencing OS-related issues, please ask for help using the Chrultrabook Forums.

Firmware

To debug firmware, you will need the following tools:

  • cbmem utility - to obtain coreboot boot logs
  • A SuzyQable - If you're experiencing severe system instability (lockups, crashes), preventing you from on-device debugging.

To dump the cbmem buffer, follow these steps:

  1. Download the cbmem utility:

    • wget https://mrchromebox.tech/files/util/cbmem.tar.gz

  2. Unzip the file and give the binary executable permissions:

    • tar -xf cbmem.tar.gz;rm cbmem.tar.gz;chmod +x cbmem

  3. Run cbmem and redirect the output to cbmem.log file:

    • sudo ./cbmem -1 > cbmem.log

  4. Provide the cbmem.log file via the chrultrabook forums, Github issue tracker, or email for further analysis.

NOTE

The parameter following the cbmem command is the number one (-1), not the letter l (-l).

SuzyQable Debug Cable

The SuzyQable provides three serial ports (UARTs) which can be accessed using a terminal utility such as minicom or picocom:

  1. CR50 console under /dev/ttyUSB0:
    • minicom -D /dev/ttyUSB0
  2. CPU console under /dev/ttyUSB1:
    • minicom -D /dev/ttyUSB1
  3. Embedded Controller (EC) console under /dev/ttyUSB2
    • minicom -D /dev/ttyUSB2

  • The CPU console can be used to debug coreboot, edk2, or the Linux kernel, but you need to re-compile coreboot with following configuration options enabled: CONSOLE_SERIAL=yEDK2_SERIAL_SUPPORT=y

  • For kernel debugging, you will also need to append the following to your kernel command line: loglevel=15 console=ttyS4,115200n8

ACPI and Linux kernelspace

  1. Download the chrultrabook debugging script.

    • cd ~/Desktop;wget https://raw.githubusercontent.com/chrultrabook/linux-tools/main/debugging.sh

    It will dump:

    • ACPI tables from sysfs (/sys/firmware/acpi/*)
    • DMI information (dmidecode)
    • Coreboot buffer (cbmem)
    • Linux kernel logs (dmesg)
    • List of PCI devices (lspci)
    • List of USB devices (lsusb)
    • Information about soundcards present in the system and their configuration

    Into debug-logs.tar.gz archive on your desktop.

  2. Run it: chmod +x debugging.sh;./debugging.sh

  3. Upload this file if you need help with troubleshooting.

gsctool

gsctool is used to communicate with the GSC (Google Security Chip) from ChromeOS and is usually used to unlock CCD without having to open up the device.

View status:

  • sudo gsctool -a -I

Unlock CCD:

  • sudo gsctool -a -o
  • This will prompt you multiple times over several minutes to press the power button. After the last time, the device will reboot back into Verified Boot Mode
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