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, you can see the code on gerrit and check it out. Issues:
- The USB beside express card cannot funtion after S3 resume (work around: reload ehci-pci module)
- Ivy Bridge processor (see below. you need to modify the config, and it needs more testing)
- RAM module combinations of 4G+0
- S3 (Suspend to RAM)
- Video (internal)
- Sound (integrated speakers, integrated mic, external headphones, external mic)
- mini-PCIe slots (wlan)
- Linux (through GRUB-as-payload)
- DVD-ROM drive
- 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: strongly recommended if you want to use an Ivy Bridge processor
- VGA option rom (optional): you need it if you want graphics 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>
Ivy Bridge processor support
Sandy Bridge and Ivy Bridge processor use the same socket, so an Ivy Bridge processor can be installed. You must modify your .config file and replace all 'SANDYBRIDGE' to 'IVYBRIDGE' to support Ivy Bridge processor, otherwise system will halt when booting. And a patch is going to be submitted so you don't need to manually modify the config file.
Up to now, an i7-3720QM(QS version) is tested. However, the native graphic init cannot work properly until kernel boots up and reinitialize the graphic system. You need the CPU microcode to make the system stable, otherwise VMX will not work and strange kernel panics will occur.