Hot answers tagged operating-systems
The "rings" nomenclature (0-3) you usually see these days started with the requested privilege level field in segment selectors as part of the design of x86 protected mode. Back in the day, it was possible to make exclusive sections of the memory space called segments. In "real mode" it was necessary since you only had 20-bit addressable memory. When ...
Ring -1 is the hypervisor, implemented as Intel VT-x ("Vanderpool") [Wikipedia] or AMD-V ("Pacifica") [Wikipedia].
Joanna Rutkowska, leader of the Qubes project, does a great job into documenting the concepts on which Qubes is relying. I therefore strongly suggest you to get the information at the source, and in particular to read the two following documents: Software compartmentalization vs. physical separation (Or why Qubes OS is more than just a random collection of ...
The direction of stack growth is hardware dependent. On x86 architectures, it grows downward, but it may be different on other architectures.
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