Install Canoeboot on Lenovo ThinkPad W541 and/or W540

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PLEASE READ THESE INSTRUCTIONS BEFORE INSTALLING, OR YOU MAY BRICK YOUR MACHINE!! - Please click the link and follow the instructions there, before flashing. For posterity, here is the link again.

This document will teach you how to install Canoeboot, on your Lenovo ThinkPad W541 and/or W540 laptop motherboard. Canoeboot is a Free Software project that replaces proprietary BIOS/UEFI firmware.

NOTE: The same image for W541 also works on the W540, as the motherboards are identical for coreboot purposes.

You can use dd to easily split your rom into the two separate portions for external flashing.

dd if=canoeboot.rom of=top.rom bs=1M skip=8
dd if=canoeboot.rom of=bottom.rom bs=1M count=8

Flash the top chip with top.rom, and the bottom chip with bottom.rom. Don’t worry about knowing which chip is which on a standard setup; flashprog will let you know if the image size is incorrect for the chip you’re flashing.

CBFS is 4MB on this board, so when external flashing, you can just break off the upper 4MB part of the image and flash that. Keep this in mind if you’re flashing externally.

When externally flashing the lower 8MB part, you can optionally flash the IFD and GbE regions if that is appropriate for your setup.

No disassembly pics yet. The W540/T540p hardware maintenance manual also applies to W541:

https://thinkpads.com/support/hmm/hmm_pdf/t540p_w540_hmm_en_sp40a26003_01.pdf

This shows disassembly. When you disassemble, and get to flashing, please note:

MOSI/MISO lines are linked between the two flash ICs, at zero ohms. This is OK for internal flashing and normal operation, because the PCH turns each chip on or off as needed, by controlling each IC’s own chip select pin, which is pin 1.

When you wire the clip, to flash one of the ICs, the same voltage rail also turns on the other IC and the other IC’s own chip-select is in a floating state, which in practise means random logic state; in other words, the other flash may or may not be active, randomly.

This means that external flashing would not ordinarily work, unless you use the following trick:

Use a test hook wired to VCC (+3.3v), to pull the other flash’s chip-select high. So: when flashing one of the two ICs, the other chip must have pin 1 connected to VCC. You can do this with the same 3.3v power source that you use on pin 8 of the chip that you’re flashing. Ideally you should pull the other chip select high via 47ohm resistor, which should be enough to prevent damage in the case of accidentally shorting the wrong pin.

Doing this means that you disable the chip you’re not flashing. It’s very important that you ensure only the one you want to flash is active, when using an external flasher.

This is not required for internal flashing. It is only required for external flashing.

If you do it right, the chips should flash reliably. This same trick must be used when flashing either of the chips.

You can now proceed to flashing this machine.

It has been reported by a user that thinkpad_acpi does not load correctly on the T440p. Since the W541/W540/T540p are also Haswell machines, you may be affected by this issue.

If you encounter this, check this page for details as to how to fix this.

Markdown file for this page: https://canoeboot.org/docs/install/w541_external.md

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