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Lenovo Yoga C940 Beta BIOS

Mirror of the (semi-)official beta-bios Lenovo released for proper audio support under Linux

📅 Created: Aug 13, 2022•🕒 Updated: Apr 12, 2024

Disclaimer: The BIOS should be the exact same which Lenovo published on Google Drive (state of 30.12.2020) but is (along with the guide) supplied without any warrenty. I am not liable if you brick your Laptop!

Notice (18.09.23): I apologize to anyone thinking this article was meant to be locked down behind an authwall, a config error resulted in this being the case for a brief time. I intended it to be and stay public, just like it is now (again). Again, sorry for the inconvenience.

How To Install ​

💾 Mirrored files: https://nextcloud.libre.moe/s/Aq3cxRAWP7Ck8HZ
Secondary mirror: https://files.langrock.info/other/Lenovo Yoga C940 Beta-BIOS for Linux/

If any of these stop working, please just write me an email or something. I'll likely still have the files somewhere and will fix the links.

  1. Download the mirrored files from the link above and extract the ZIP-archive.

  2. Set up a USB stick with a single FAT 32 partition.

  3. Unzip shell file.zip. This archive has the necessary files to boot your Lenovo C940 to a state that it can load the BIOS file.

  4. Copy the resulting files and directories to the USB stick

  5. The BIOS itself is in C940AudioTest.7z.
    Use 7z x C940AudioTest.7z to unpack this archive.

  6. Copy AUCN57WW.efi to the USB stick.

  7. Turn off your C940.

  8. Use Fn + Power Button to boot in to the NOLO (sp?) interface.

  9. Press ESC to skip startup.nsh. (You only have about three seconds.)

  10. Input fs0: to go to the USB stick directory.

  11. Input AUCN57WW.efi to flash the new BIOS.

Further help ​

This guide was originally posted on the Kernel.org Bugzilla. In case this guide doesn't work as intended or you need some further assistance, it might be helpful to check out the thread there.

Checksums ​

You can use these checkums to check if your download is identical to the files I uploaded. Please verify that the checksums are identical to make sure your download was not corrupted.

FileMD5SHA1
C940AudioTest (BIOS).7z8394a5cd417afce674a11ee7baad18a7a54419d7c9682dbe6817990763bc1100b7792a83
shell file (flash tool).zip15d6a99d4d279f28948279fe605d59c5983474708085b0eca1e824e6d1501cdc21066fa0

These checksums were generated using Dolphin v22.04.01.

Archived Comments

Johannes•Mar 9, 2024
Hey, I tried to follow your instruction but it seems like there some step missing between 8. and 9. I'm getting in to the NOLO interface, but where (in which menu or so) exactly do I have to press ESC ? Thanks a lot for your Help
Lukas Langrock•Apr 12, 2024
Hi, it's been ages since I did this myself and the instructions aren't written by me. I just did a quick test on my C940 and I think you are supposed to enter the boot menu (by navigating using arrow keys and enter) and select your USB-stick from the list. If I recall correctly, a kind of command prompt / text interface will appear, in which you will have to press ESC to skip an automatic process.