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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 X220 port. Issues:
- no MRC cache (longer boot time)
- yellow USB port isn't powered in power-off state.
- Badly seated RAM may prevent booting (not really a problem but coreboot is more suspicious to this than vendor BIOS)
- No wifi on windows
Tested (and works):
- RAM module combinations of 4G+0, 4G+4G
- S3 (Suspend to RAM)
- digitizer on x220t variant
- WLAN (first minipcie slot)
- Linux (through GRUB-as-payload)
- Fn hotkeys
- Video (both internal and VGA, including native gfx init)
- battery indicator
- Fingerprint reader.
- Thermal management
- Expresscard slot (including hotplugging)
- USB (all 3 ports)
- SD card slot
- Sound (integrated speakers, integrated mic, external headphones, external mic)
- WLAN slot USB
- Windows (through SeaBIOS; you have to use extracted VGA blob, dumped from memory isn't good enough)
- displayport (probably works)
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)
X220 has 1 flash chip of 8M. It's subdivided in roughly in 3 parts:
- Descriptor (12K)
- ME firmware (5M-12K)
- System flash (7M)
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).
- X220 chip.jpg
Proceeds as follows:
- Turn off your laptop, remove battery and AC adapter.
- Remove the keyboard.
- Connect your external SPI flasher to the top SPI chip which is under palm resting space, on left side of the board. It's a 8M chip.
I recommend using SOIC clip. Depending on the flasher you use, you may have to use separate 3.3V source. Make sure not to feed more than 3.3V ot the chip. I used buspirate as flasher and 3.3V power lines from another computer.
- Read the flash. Twice. Compare the files to be sure. Save a copy of it on
flashrom -p <yourprogrammer> -r flash.bin flashrom -p <yourprogrammer> -r flash2.bin diff flash.bin flash2.bin
If they don't match, do not proceed.
- Recover descriptor and me firmare:
dd if=flash.bin of=coreboot/3rdparty/mainboard/lenovo/x220/descriptor.bin \ count=12288 bs=1M iflag=count_bytes dd if=flash.bin of=coreboot/3rdparty/mainboard/lenovo/x220/me.bin \ skip=12288 count=5230592 bs=1M iflag=count_bytes,skip_bytes
- Compile coreboot
- Flash the resulting build/coreboot.rom
If you have trouble reading the chip successfully, the most common problems are
- insufficient power supply
- bad contacts
- too long wires
- bad pinout
The cable shipped with buspirate was too long, and needed to be trimmed.
See also In-System Programming