Debugging

Grabbing Logs

• If you are experiencing firmware bugs, provide output from cbmem console.
• If you are experiencing issues with Linux, provide output from dmesg, dmidecode and journalctl or /var/log/messages, respectively
• If you are experiencing issues with Windows, provide screenshots from Device Manager, Event Viewer, coredumps etc.
• If you are experiencing issues with macOS, please ask for help using the Chrultrabook Forums.

Firmware

To debug firmware, you will need the following tools:

1. cbmem - To view Coreboot logs
2. ectool - To interface with ChromeOS Embedded Controller
3. SuzyQ - If you are experiencing severe system instability (lockups, crashes), preventing you from on-device debugging.

To dump the cbmem buffer, follow these steps:

1. Download the tar archive from MrChromebox's website:
   • 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 pipe its output to cbmem.log file:
   • sudo ./cbmem -1 > cbmem.log
4. Upload cbmem.log file for further analysis.

To interface with the Embedded Controller:

1. Download the tar archive from MrChromebox's website:
   • wget https://mrchromebox.tech/files/util/ectool.tar.gz
2. Unzip the file and give the binary executable permissions:
   • tar -xf ectool.tar.gz;rm ectool.tar.gz;chmod +x ectool
3. Issue commands to EC by executing commands, for example setting the fan to 100%:
   • sudo ./ectool --name=cros_ec fanduty 100
   • Running ./ectool help will provide you with a list of available commands, or you can take a look at ectool's source code directly

SuzyQ Debug Cable

If you need to use SuzyQ, you can use minicom or picocom for example. It exposes three serial devices:

1. AP (CR50) console under /dev/ttyUSB0:
   • minicom -D /dev/ttyUSB0 -b 115200
2. Coreboot/platform serial under /dev/ttyUSB1:
   • minicom -D /dev/ttyUSB1 -b 115200
3. Embedded Controller console under /dev/ttyUSB2
   • minicom -D /dev/ttyUSB2 -b 115200

• Platform serial can be used to debug the payload or kernel, but you need to re-compile coreboot with following configuration options enabled: CONSOLE_SERIAL=yEDK2_SERIAL_SUPPORT=y
• To use SuzyQ as platform debugger, you will also need to append the following to your kernel commandline: loglevel=15 console=ttyS4,115200n8

ACPI and Linux kernelspace

1. Download our 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.

   • Remember to remove WiFi information from dmesg to protect your privacy.

flashrom

Flashrom is used to read and write from the SPI flash

Read flash

• sudo flashrom -p <programmer> -r <filename.rom>
• Example:
  • sudo flashrom -p internal -r backup.rom

DANGER

If you have an Intel Chromebook, you will need to add --ifd -i bios if you want to write to the flash or else flashrom will fail.

Write flash

• sudo flashrom -p <programmer> -w <filename.rom>
• Intel Example:
  • sudo flashrom -p internal --ifd -i bios -w stock.rom
• AMD Example:
  • sudo flashrom -p internal -w stock.rom

Write protection

View status:

• sudo flashrom -p internal --wp-status

Enable WP:

• sudo flashrom -p internal --wp-enable

Disable WP:

• sudo flashrom -p internal --wp-disable

Clear WP range:

• sudo flashrom -p internal --wp-range 0 0

Common programmers:

• internal: Use this when you run flashrom on the chromebook you want to program.
• ch341a_spi: Use this when you use a ch341a external programmer.
• raiden_debug_spi:target=AP: Use then when you want to flash using a Suzy-Q cable.

gsctool

gsctool is used to communicate with the GSC (Google Security Chip) from ChromeOS and is usually used to unlock CCD without removing the back of the Chromebook.

View status:

• sudo gsctool -a -I

Unlock CCD:

• sudo gsctool -a -o
• This will prompt you multiple times to press the power button, on the last time, the device will reboot back into verified mode