Narcis Garcia <informatica@???> wrote:

> As Far As I Know, CPU makes what software asks to do.
> If software doesn't call some CPU functions, those functions will not work.

Well, maybe, but these days you can't take that on trust. Your OS no longer runs native on the processor - there's EFI as a shim between your code and the processor, hence no guarantees that *ONLY* your code is running. As a side effect, the EFI can permit or deny access to processor functions as well - eg by disabling the virtualisation support features for "entry level" machines.
So these days, you can't assume that there isn't any form of backdoor - with hidden code in the EFI, using hidden functions in the CPU, and making backdoor use of the onboard NIC to call out to someone. OK, that's perhaps into "tinfoil hat" territory - but the point is that we can no longer completely trust the hardware we supposedly buy (sometimes feels like rental !)