If we are to assume that we know exactly how many negative protection rings exist (be it -4 or -5, the bottom one) and that we were to control them all, does it mean that we should not be worrying about all the other HW components with closed source firmwares (except those who do compute, like GPUs)?
Why I’m asking the question? Because of the recent info I leaned:
- Mostly all HW components of a computer have their own firmware, which sure is not freedom-respecting simply because it’s closed sourced.
- Protection Rings which consist of at least 7 rings are very important, security-wise and it’s dependent on the control we have over the CPU and the chipset. The lower the ring is that we control, the more control we have on the rest of them, for example, ring -4 controls -3, -2 … 3.
Finding out these two pieces of information, made me question if we’ll need eventually to work on freeing all the firmwares, or it is enough to have complete control over the chipset and the CPU.