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Flashing coreboot on a Lenovo Thinkpad X220 with a ch341a USB programmer Tutorial

In this tutorial, we will go through the steps to get coreboot compiled and flashed on a Lenovo Thinkpad X220 laptop. We'll also change the Wifi card so that Wifi will work with a libre kernel driver.

Prerequisites

Prerequisites

Things you need:

  • Lenovo Thinkpad X220
  • Atheros AR9382 AR5BHB116 Mini PCIE Dual Band Wifi card
  • ch341a USB programmer
  • Pomona 5250 SOIC-8 clip
  • 6 x 10 cm female - female jumper wires
  • Screwdriver

Files needed:

dejavusansmono.pf2
grub.cfg
background.jpg

For more information about DejaVu Fonts, see:
https://dejavu-fonts.github.io/

For DejaVu Font license, see:
https://dejavu-fonts.github.io/License.html

'background.jpg' is borrowed from the libreboot project and it's license information is as follows:

These images are based on http://libreboot.org/logo/logo.svg
which is Copyright 2014 Marcus Moeller and released under CC-0
https://creativecommons.org/publicdomain/zero/1.0/legalcode

Packages needed to compile flashrom/coreboot/grub

sudo apt-get install git build-essential gnat flex bison libncurses5-dev wget libpci-dev libusb-dev libftdi1 libftdi-dev unifont zlib1g-dev

Compile flashrom

Clone flashrom git repository:

git clone https://review.coreboot.org/flashrom.git

Compile flashrom:

cd flashrom
make -j4
sudo make install
sudo cp /usr/local/sbin/flashrom /usr/local/bin/

Compile GRUB

See 'Prerequisites' above for the files needed.

Clone GRUB git repository:

git clone https://git.savannah.gnu.org/git/grub.git

Compile GRUB:

cd grub
git checkout grub-2.02
./autogen.sh
./configure --with-platform=coreboot
make -j4

Create 'pack-payload-minimal.sh' script file:

touch pack-payload-minimal.sh
chmod +x pack-payload-minimal.sh

Paste the following in 'pack-payload-minimal.sh':

#! /bin/bash

# ./pack-payload-minimal.sh – To be invoked within GRUB project folder, packs
# an executable elf payload file for the coreboot project, using just one
# keyboard layout file. Adapt “settings” to your needs. Specify a lighter
# pf2-fontfile if available on your system.

# settings
elf_output="grub2.elf"
#pf2_fontfile="unicode.pf2"
pf2_fontfile="dejavusansmono.pf2"
keyboard_layout="se"
grub_modules="cbfs"

# generate keyboard layout
ckbcomp "${keyboard_layout}" | ./grub-mklayout -o "${keyboard_layout}.gkb"

# pack the GRUB payload file
./grub-mkstandalone \
        --grub-mkimage=./grub-mkimage \
        -O i386-coreboot \
        -o "${elf_output}" \
        -d grub-core \
        --fonts= \
        --themes= \
        --locales= \
        --modules="${grub_modules}" \
        /boot/grub/grub.cfg=coreboot.cfg \
        /boot/grub/fonts/${pf2_fontfile}="${pf2_fontfile}" \
        /boot/grub/layouts/${keyboard_layout}.gkb="${keyboard_layout}.gkb"

# message
echo "Payload ${elf_output} has been packed with:"
echo " * fontfile: ${pf2_fontfile}"
echo " * keyboard layout: ${keyboard_layout}"
echo " * GRUB modules, to be preloaded: ${grub_modules}"

# code snippet suggestion
echo "Don't forget to add 'keymap ${keyboard_layout}' to your GRUB Configuration File."

# clean up
rm "${keyboard_layout}.gkb"

Execute the script to create 'grub2.elf' file:

./pack-payload-minimal.sh

Connect ch341a USB programmer to flash chip

Remove the following parts to access the flash chip:

Battery
Keyboard
Palmrest

Connect ch341a USB programmer

Connect Pomona 5250 to flash chip like this:

Screen (furthest from you)
             __
  MOSI  5 --|  |-- 4  GND
   CLK  6 --|  |-- 3  N/C
   N/C  7 --|  |-- 2  MISO
   VCC  8 --|__|-- 1  CS

   Edge (closest to you)

ch341a USB programmer connected

Read Factory BIOS

Read Factory BIOS 3 times:

sudo flashrom -p ch341a_spi -r factory_bios_01.rom -V
sudo flashrom -p ch341a_spi -r factory_bios_02.rom -V
sudo flashrom -p ch341a_spi -r factory_bios_03.rom -V

Make sure checksums are identical:

sha512sum *.rom

Download coreboot

Download coreboot:

wget https://coreboot.org/releases/coreboot-4.9.tar.xz
wget https://coreboot.org/releases/coreboot-blobs-4.9.tar.xz

Extract coreboot and blobs needed:

tar xvf coreboot-4.9.tar.xz
tar xvf coreboot-blobs-4.9.tar.xz --strip-components=1 -C coreboot-4.9

Create folder to hold 'descriptor/gbe/me.bin' files:

mkdir -pv coreboot-4.9/3rdparty/blobs/mainboard/lenovo/x220/

Extract blob files from Factory BIOS (see 'flashrom/util/ich_descriptors_tool' folder:

cd ~/misc-src/flashrom/util/ich_descriptors_tool
./ich_descriptors_tool -f your/path/to/factory_bios.rom -d

Copy blob files to coreboot folder:

cp factory_bios.rom.Descriptor.bin coreboot-4.9/3rdparty/blobs/mainboard/lenovo/x220/descriptor.bin
cp factory_bios.rom.GbE.bin coreboot-4.9/3rdparty/blobs/mainboard/lenovo/x220/gbe.bin
cp factory_bios.rom.ME.bin coreboot-4.9/3rdparty/blobs/mainboard/lenovo/x220/me.bin

Setup and compile coreboot

Enter coreboot folder:

cd coreboot-4.9

Build toolchain needed first (this will take a long time, be patient):

make crossgcc CPUS=4

coreboot settings menu:

make menuconfig

Set the following options:

NOTE: Leave default values as is and specifically set the following
options:

general  --|
           |-[*] Use CMOS for configuration values
mainboard -|
           |-Mainboard vendor (Lenovo)
           |-Mainboard model (ThinkPad X220)
           |-ROM chip size (8192 KB (8 MB))
           |-(0x300000) Size of CBFS filesystem in ROM
chipset ---|
           |-Include CPU microcode in CBFS (Do not include microcode updates)
           |-[*] Add Intel descriptor.bin file (leave default path as is)
           |-(3rdparty/blobs/mainboard/$(MAINBOARDDIR)/descriptor.bin) Path and filename of the descriptor.bin file
           |-[*] Add Intel ME/TXE firmware (leave default path as is)
           |-(3rdparty/blobs/mainboard/$(MAINBOARDDIR)/me.bin) Path to management engine firmware
           |-    [*] Verify the integrity of the supplied ME/TXE firmware
           |-    [*] Strip down the Intel ME/TXE firmware
           |-[*] Add gigabit ethernet firmware (leave default path as is)
           |-(3rdparty/blobs/mainboard/$(MAINBOARDDIR)/gbe.bin) Path to gigabit ethernet firmware
Devices ---|
           |-Graphics initialization (Use native graphics init)
           |-Display
           |-    Framebuffer mode (Linear "high-resolution" framebuffer)
payload ---|
           |-Add a payload (An ELF executable payload)
           |-"(grub2.elf)" Payload path and filename

If you want to include CPU microcode updates:

chipset ---|
           |-Include CPU microcode in CBFS (Generate from tree)

This will create a '.config' file containing all settings.

Compile coreboot:

make -j4

This will create 'build/coreboot.rom' image with the size of 8mb.

Add custom files to 'coreboot.rom' image

Add 'grub.cfg' and 'background.jpg' to coreboot.rom. See 'Prerequisites' above for the files needed.

Make sure 'cbfstool' is built:

cd coreboot-4.9/util/cbfstool 
make -j4

Add custom GRUB configuration file:

./cbfstool ../../build/coreboot.rom add -t raw -n etc/grub.cfg -f your/path/to/grub.cfg

Check so that 'etc/grub.cfg' exists in coreboot.rom:

./cbfstool ../../build/coreboot.rom print

Add background image:

./cbfstool ../../build/coreboot.rom add -t raw -n background.jpg -f your/path/to/background.jpg

Check so that 'background.jpg' exists in coreboot.rom:

./cbfstool ../../build/coreboot.rom print

Tweak parameters in 'cmos.default'

Make sure 'nvramtool' is built:

cd coreboot-4.9/util/nvramtool
make -j4

Get an overview of tweakable parameters:

./nvramtool -C ../../build/coreboot.rom -a

Tweak values we need:

./nvramtool -C ../../build/coreboot.rom -w gfx_uma_size=224M
./nvramtool -C ../../build/coreboot.rom -w wwan=Disable
./nvramtool -C ../../build/coreboot.rom -w bluetooth=Disable
./nvramtool -C ../../build/coreboot.rom -w touchpad=Disable

Check specific parameter possible values:

./nvramtool -C ../../build/coreboot.rom -e gfx_uma_size

Make sure values are changed:

./nvramtool -C ../../build/coreboot.rom -a

Done! Now it's time to flash the new 'coreboot.rom' image!

Flash coreboot image

See 'Connect ch341a USB programmer to flash chip' for details on how to connect ch341a USB programmer.

Flash coreboot using ch341a USB programmer:

sudo flashrom -p ch341a_spi -w coreboot.rom -V

Change Wifi card

Remove the following parts to access the Wifi card:

Battery
Keyboard
Palmrest

See 'Connect ch341a USB programmer to flash chip' for details on where the Wifi card is located.

Congratulations! We're done. Now you can install a libre distro such as Debian GNU/Linux. I recommend setting up full disc encryption (including /boot) ! The 'grub.cfg' supports and defaults to this option.

Recommended reading

https://www.coreboot.org/
https://libreboot.org/
https://flashrom.org/Flashrom
https://www.thinkwiki.org/wiki/Category:X220
https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/0a60739.pdf
https://github.com/boseji/CH341-Store
https://libreboot.org/docs/gnulinux/encrypted_debian.html
https://dejavu-fonts.github.io/
https://dejavu-fonts.github.io/License.html

Posted on Tue, 2 Apr 2019
Tags: ch341a, coreboot, flashrom, lenovo-thinkpad-x220, libreboot



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