lbwww/site/docs/install/w541_external.md

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ThinkPad W541/W540 external flashing	true

Please follow this prior to flashing, or you may brick your machine.

Please inject vendor files prior to flashing. You can also use this guide to change the built-in MAC address for your Intel Gigabit Ethernet device; doing so is advisable, because otherwise you will have a default, generic MAC address.

Splitting The Rom

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

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

Flash the top chip with top.rom, and tho 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.

Disassembly

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 fou'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.

thinkpad_acpi issues

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.

Errata

NOTE: As of Libreboot releases from May 2024 onward, the Intel MRC is no longer included for Haswell; MRC is a blob for raminit, but we now provide libre raminit. The following targets no longer exist in the build system:

• t440pmrc_12mb (use t440plibremrc_12mb instead)
• t440pbmrc_12mb (use t440plibremrc_12mb instead)
• w541mrc_12mb (use w541_12mb instead)
• w541bmrc_12mb (use w541_12mb instead)
• dell9020sff_12mb (use dell9020sff_nri_12mb instead)
• dell9020sffbmrc (use dell9020sff_nri_12mb instead)
• dell9020mt_12mb (use dell9020mt_nri_12mb instead)
• dell9020mtbmrc (use dell9020mt_nri_12mb instead)

This is written as errata because some users may still be using older release images but on the newer build system from May 2024 onward; you must use the Libreboot 20240225 release if you want to inject MRC and so on, for these older targets.

Libreboot's binary blob reduction policy is very strict, and states: if a blob can be avoided, it must be avoided. Therefore, the MRC is removed on Haswell and Libreboot will only use the libre raminit (called NRI, short for Native Ram Initialisation).