Lenovo has denied locking its Signature Edition PCs exclusively to Windows 10 under orders from Microsoft.

A Reddit thread this morning accuses Microsoft and Lenovo of conspiring to prevent the installation of non-Windows operating systems on the Chinese goliath's PCs at the firmware level. Linux fans vented on the message board about the difficulties of installing open-source distributions on certain Lenovo machines.

Several users noted certain new Lenovo computers’ SSDs are locked in a RAID mode, with AHCI support disabled from the firmware, and there's no way to change this configuration. Windows is able to see the SSD while in RAID mode due to a proprietary Intel driver, but the SSD is hidden from Linux installations because the necessary driver is unavailable. This prevents GNU/Linux operating systems from being installed on new Lenovo machines, the users said, and "locks" them to the Windows 10 Home OS.

(Matthew Garrett, a Linux kernel expert, has published some more technical info here.)

So, it appears we're looking at a storage driver compatibility problem. What set the cat among the pigeons today, though, is this response by a "Lenovo Product Expert" to a review of Lenovo's Yoga 900 ISK2 model on Best Buy's website. The reply explains to an aggrieved customer that the Signature Edition machine cannot install anything other than Windows 10 Home due to a deal with Microsoft:

This system has a Signature Edition of Windows 10 Home installed. It is locked per our agreement with Microsoft.

Speaking to The Register today, a Lenovo spokesperson claimed the Chinese giant "does not intentionally block customers using other operating systems on its devices and is fully committed to providing Linux certifications and installation guidance on a wide range of products."

Then why the RAID issue? The spokesperson told us: "To improve system performance, Lenovo is leading an industry trend of adopting RAID on the SSDs in certain product configurations."

"Unsupported models will rely on Linux operating system vendors releasing new kernel and drivers to support features such as RAID on SSD," he added. "Unfortunately, I cannot confirm our relationship to the person at Best Buy."

Basically, if you want to install Linux, you need a kernel with the required SSD driver.

Firmware shenanigans at Lenovo are something of a recurring issue. Last year, Lenovo was found to be bundling unremovable crapware onto Windows laptops, which the machines' firmware reinstalled if users attempted to get rid of it. Of course, this turned out to contain an exploitable security vulnerability too.

Complaints on Lenovo's forums suggest that users have been unable to install GNU/Linux operating systems on models from the Yoga 900S to the Ideapad 710S, with one 19-page thread going into detail about the firmware issue and users' attempts to work around it.

The Reddit user wrote that "the Yoga 900 ISK2 at Best Buy is not labeled as a Signature Edition PC, but apparently it is one, and Lenovo's agreement with Microsoft includes making sure Linux can't be installed."

Lenovo's Signature Edition machines are sold without the PC maker's usual bloatware crap.

El Reg contacted Microsoft this morning but it had still not responded to our enquiries at the time of publication. ®