Fresh from a €561 million fine for failing to comply with a previous antitrust agreement, Microsoft is once again being targeted in Europe over their allegedly anti-competitive business practices. This time the complaint focuses on Microsoft's implementation of UEFI Secure Boot for Windows 8, which according to Spanish open source software group Hispalinux, is an obstruction mechanism to prevent alternative OS installations.

The feature in question is an industry initiative designed as an alternative to the aging BIOS that improves security against boot loader attacks by only running software signed with a trusted certificate. With the release of Windows 8 last year, Microsoft started requiring UEFI on machines carrying the "Certified for Windows 8" logo.

While OEMs have the option of providing a way to turn off UEFI so other operating systems can run on the machine, many in the Linux community feared that companies would not provide a UEFI off-switch. That may vary from one manufacturer to another, but in practice this hasn't stopped many people from booting Linux.

The Linux Foundation and others have provided workarounds that let Linux-based operating systems boot without disabling the security mechanism, including one that involves Microsoft-signed binary keys that are dynamically added to the Linux kernel. But some members of the Linux community have been vocal against solutions like this, with Linus Torvalds calling it "moronic" arguing Microsoft could arbitrarily disable the key.

Whether Hispalinux's 14-page complaint with the European Commission holds any merit remains to be seen, but it appears to cover much the same ground. "The fact is that no software or operating system that needs the boot system to install or work, will be able to access the computer without Microsoft's prior permission," the group argued in a blog post, adding that this is "completely unjustified."

Hispalinux is asking the European Commission to grant a preliminary injunction requiring Microsoft to modify its requirement for manufacturers to implement Microsoft's UEFI Secure Boot.