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Would there be any merit in the OS hiding what CPU brand? Keep exposing what specific CPU features/instruction sets are supported but don't display whether it i

Would there be any merit in the OS hiding what CPU brand? Keep exposing what specific CPU features/instruction sets are supported but don't display whether it is AMD/Intel/Via. What's the benefit? I find it hard to believe there are many "optimizations" out there that despite the instruction sets being the same do different things based on the specific CPU model or brand. If I'm wrong and there is a substantial amount of software that requires that then perhaps it can be hidden behind some kind of request access popup.

paol 7y ago
First, the OS can't hide that because it's not a middleman in the execution of program code. When a program is running on a CPU it has access to the instructions that tell it what CPU it is. Second, there are already many ways for programs to get granular CPU feature information. It's entirely the software's fault if it decides to ignore that information and instead use a big "if" switch keyed solely on the manufacturer.
- pmjordan 7y ago
  First, the OS can't hide that because it's not a middleman in the execution of program code. When a program is running on a CPU it has access to the instructions that tell it what CPU it is. Technically, it could, using virtualisation extensions to x86. CPUID can be trapped by a hypervisor, and the hypervisor can supply whatever result it likes. This is how Qemu/KVM simulates different CPU models. Mainstream OSes don’t use virtualisation extensions for regular processes of course, and hypercalls would be even more expensive than regular syscall based context switches, so this is probably not something that is going to change in the short to medium term.
  - jotm 7y ago
    Could Windows 10 with Hyper V enabled do it? They claim native performance when running it
    - Filligree 7y ago
      No, they're just lying. You can get close, but you'll never achieve quite the same performance.

paol 7y ago

First, the OS can't hide that because it's not a middleman in the execution of program code. When a program is running on a CPU it has access to the instructions that tell it what CPU it is. Second, there are already many ways for programs to get granular CPU feature information. It's entirely the software's fault if it decides to ignore that information and instead use a big "if" switch keyed solely on the manufacturer.

pmjordan 7y ago
First, the OS can't hide that because it's not a middleman in the execution of program code. When a program is running on a CPU it has access to the instructions that tell it what CPU it is. Technically, it could, using virtualisation extensions to x86. CPUID can be trapped by a hypervisor, and the hypervisor can supply whatever result it likes. This is how Qemu/KVM simulates different CPU models. Mainstream OSes don’t use virtualisation extensions for regular processes of course, and hypercalls would be even more expensive than regular syscall based context switches, so this is probably not something that is going to change in the short to medium term.
- jotm 7y ago
  Could Windows 10 with Hyper V enabled do it? They claim native performance when running it
  - Filligree 7y ago
    No, they're just lying. You can get close, but you'll never achieve quite the same performance.