hmm.. so the kernel needs to export all the cpuid info (that the kernel
enables and supports) to the user through some mechanism then?
For a cheap interface, we use AT_HWCAP for this. Unfortunately that only
covers the first 32 bits of CPUID info. (For another cheap interface,
giving all the CPUID bits in the vDSO would be easy.)
For a clunky interface that already exists and is "simple" to use,
there is /dev/cpu/0/cpuid now. I wonder if having a device node and
opening it too much for applications that consider the vDSO too complex.