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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!
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)
- S3 (Suspend to RAM)
- RAM module combinations of 4G+0
- Video (internal)
- Sound (integrated speakers, integrated mic, external headphones, external mic)
- mini-PCIe slots (wlan)
- Linux (through GRUB-as-payload)
- SD card slot
- Fn hotkeys (backlight control, suspend, thinklight)
- dock (tested with a TYPE 4337)
- Video (VGA and Displayport)
- Expresscard slot (including hotplugging)
- mini pci-e wwan
- Fingerprint reader.
- Thermal management
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)
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>