Microsoft claimed that there would be no problems using rival operating systems alongside its UEFI secure boot system, however, according to Software Freedom, Microsoft has wasted no time in revising its Windows Hardware Certification Requirements to effectively ban most alternative operating systems on ARM-based devices that ship with Windows 8.
According to Microsoft, its Certification Requirements allow for a "custom" secure boot mode, in which a physically present user can add signatures for alternative operating systems to the system's signature database. But it seems that for ARM devices, Custom Mode is prohibited.
The requirements say that only Standard [Windows] Mode may be enabled and users will not have the choice to simply disable secure boot, as they will on non-ARM systems.
To make it clearer, Microsoft said that disabling Secure Boot "must not" be possible on ARM systems, according to the group.
In other words, any ARM gear that ships with Windows 8 will never run another operating system, unless it is signed with a preloaded key or is jailbroken.
The Software Freedom group said that Microsoft is using a different set of hardware partners when it uses ARM chips. It has done these deals because all of the handsets running the Windows Phone operating system are ARM-based.
But on the PC, where its partner is Intel, Microsoft's secure boot requirements, which allow users to add signatures in Custom Mode or disable secure boot entirely, are close to what everyone wants.
This is because, claims the Software Freedom group, that Microsoft does not need to support legacy Windows versions on ARM. If Microsoft locked unsigned operating systems out of new PCs, it would risk angering its own customers who prefer Windows XP or Windows 7. Since it does not have to support legacy versions to run on ARM, Microsoft is eager to lock users out, the outfit claims.
"It is clear now that opportunism, not philosophy, is guiding Microsoft's secure boot policy," it was claimed.