Dupe: https://news.ycombinator.com/item?id=44601045

Is there a reason why the secure boot thing could not have had several secure boot slots and each one independent of others? So that microsoft world could run securely and other people could boot their system securely out of another slot?

Just wondering what the technical reason would be that Microsoft had to control the whole of the PC??

Surely, the control of the boot environment and any the the boot shims could have been restricted to system that could boot out of said shim. Then the two worlds could have securely co-existed could they not ?