If you're using libreboot from git, note that only CrOS devices build at the moment. We merged a newly rewritten build system recently, and we've yet to complete re-integration of older boards into Libreboot. Use Libreboot 20160907 for the time being, unless you're involved in libreboot development

# ThinkPad T400

It is believed that all or most T400 laptops are compatible. See notes about CPU compatibility for potential incompatibilities.

There are two possible flash chip sizes for the T400: 4MiB (32Mbit) or 8MiB (64Mbit). This can be identified by the type of flash chip below the palmrest: 4MiB is SOIC-8, 8MiB is SOIC-16.

The T400 laptops come with the ME (and sometimes AMT in addition) before flashing libreboot. Libreboot disables and removes it by using a modified descriptor: see gm45_remove_me.html (contains notes, plus instructions)

Flashing instructions can be found at ../install/#flashrom

Back to previous index.

# EC update

It is recommended that you update to the latest EC firmware version. The EC firmware is separate from libreboot, so we don't actually provide that, but if you still have Lenovo BIOS then you can just run the Lenovo BIOS update utility, which will update both the BIOS and EC version. See:

- https://libreboot.org/docs/install/index.html#flashrom
- http://www.thinkwiki.org/wiki/BIOS_update_without_optical_disk

NOTE: this can only be done when you are using Lenovo BIOS. How to update the EC firmware while running libreboot is unknown. Libreboot only replaces the BIOS firmware, not EC.

Updated EC firmware has several advantages e.g. bettery battery handling.

## Compatibility (without blobs)

### Hardware virtualization (vt-x)

The T400, when run without CPU microcode updates in coreboot, currently kernel panics if running QEMU with vt-x enabled on 2 cores for the guest. With a single core enabled for the guest, the guest panics (but the host is fine). Working around this in QEMU might be possible; if not, software virtualization should work fine (it's just slower).

On GM45 hardware (with libreboot), make sure that the kvm and kvm_intel kernel modules are not loaded, when using QEMU.

The following errata datasheet from Intel might help with investigation: http://download.intel.com/design/mobile/specupdt/320121.pdf

The T400 is almost identical to the X200, code-wise. See x200.html.

## Hardware register dumps

The coreboot wiki shows how to collect various logs useful in porting to new boards. Following are outputs from the T400:

- T400 with Winbond W25X64 flash chip (8MiB, SOIC-16) and Lenovo BIOS 2.02 (EC firmware 1.01):
  - ../future/dumps/logs-t400-bios2.02-ec1.01/
- Version of flashrom used for the external flashing/reading logs is the one that libreboot git revision c164960 uses.

Copyright © 2015 Leah Rowe <info@minifree.org>
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