Board:lenovo/t420

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The wiki is being retired!

Documentation is now handled by the same processes we use for code: Add something to the Documentation/ directory in the coreboot repo, and it will be rendered to https://doc.coreboot.org/. Contributions welcome!

Status

Thanks for your interest in Lenovo T420 port. The code has not been merged yet. Issues:

  • The USB beside express card cannot funtion after S3 resume (work around: reload ehci-pci module)

Tested:

  • S3 (Suspend to RAM)
  • RAM module combinations of 4G+0
  • USB
  • Video (internal)
  • Sound (integrated speakers, integrated mic, external headphones, external mic)
  • mini-PCIe slots (wlan)
  • Linux (through GRUB-as-payload)
  • SD card slot
  • trackpoint
  • touchpad
  • Fn hotkeys (backlight control, suspend, thinklight)
  • Thinklight
  • dock (tested with a TYPE 4337)

Not Tested:

  • Video (VGA and Displayport)
  • Expresscard slot (including hotplugging)
  • Windows
  • mini pci-e wwan
  • LAN
  • Fingerprint reader.
  • Webcam
  • Thermal management
  • bluetooth
  • msata

proprietary components status

  • CPU Microcode
  • VGA option rom (optional): you need it if you wantgraphics in SeaBIOS but most payloads should work without it (text mode or corebootfb mode)
  • ME(Management Engine) => you do not have to touch it(just leave it where it is)
  • EC(Embedded Controller) => you do not have to touch it(just leave it where it is)

Flashing

T420 has an SOIC-8 flash chip of 8M. It's subdivided in roughly in 3 parts:

  • Descriptor (12K)
  • ME firmware (5M-12K)
  • System flash (3M)

ME firmware is not readable. Vendor firmware locks the flash and so you need to flash externally (unless until someone figures out a way around it).

Proceeds as follows:

  • Turn off your laptop, remove battery and AC adapter.
  • Disassemble the T420 laptop as the hardware maintenance manual says. You have to take out the mainboard, because the flash chip is under the magnesium stucture frame.
  • Connect your external SPI flasher to the SPI chip and flash it. Using an SOIC-8 clip is recommended.

When the laptop is running coreboot, you can reflash the firmware using flashrom:

 flashrom -p internal:laptop=force_I_want_a_brick -w <coreboot image>