Linux provides /dev/random and /dev/urandom to all applications as well as relevant API calls, but the quality of those is always in doubt (especially with urandom, which recycles the entropy pool when it gets too low). CPU hardware PRNGs are supposed to be much higher quality, when they work. So it's all about depending on the CPU to actually do what it's advertising - the CPUID flag advertises a high-quality hardware RNG, but then the firmware bug completely nurfs it.