Add support for/ flesh out a lot of other x86 vendors (Centaur/Cyrix/Rise/Zhaoxin)

[timw4mail]

I'm not going to make this a PR directly, as there are a large number of changes, and PRs are denied by default.

I have a fork here: master...timw4mail:cpufetch:retrox86
(I merged in the @danielinux Transmeta changes before I rebased on the most recent changes, I'm not trying to taking credit for those).

I'm willing to split into multiple PRs of more limited scope to make things easier. I have verified CPUs that I've added with real hardware, other than the IDT Winchips (as I haven't been able to get a linux distro to boot on that architecture).

[Dr-Noob]

Thank you for your interest in the project, this seems like an interesting addition to the project!

I had a look at your branch and it seems like we could split it into the following contributions:

• Support for Centaur
• Support for Cyrix
• Support for Rise
• Support for Zhaoxin
• Easter egg detection in AMD

Please let me know if I missed something. I think the best would be to open separate PR for each of those like you suggested. I would create and merge one by one, if you are okay with that (I don't mind the order). Regarding the support for old x86 vendors, I need two additional things (open for discussion):

• Add proper documentation here. It's very important to keep documented how detection works for each vendor. For the time being I think you could create a new file, DOCUMENTATION_X86_retro.md and add a section for every vendor. I don't need super specific details about everything, but more a general overview and, specially, the online source you used to find all the necessary information. This can actually be used as your description for the PR, i.e., I'll have a look at the documentation to understand how your PR is implemented.
• Move the implementation of these new vendors into a new file, something like cpuid_extra.c. Same for uarch, move it to uarch_extra.c. I prefer to have cpuid.c/uarch.c for mainstream vendors (Intel/AMD) and the rest (which will rarely be updated) into a separate file to keep things cleaner.

[timw4mail]

Yeah, that seems pretty reasonable.

I think more likely I'd split the changes more along these lines:

• Retro updates for Intel/AMD (Pentium Pro and K5 detection)
• Support for Centaur/Zhaoxin (Zhaoxin pretty much has Centaur behavior)
• Support for Misc. Retro vendors (Rise, UMC)
• Support for Easter Egg strings (AMD and Rise)
• Support for Cyrix/ST

As for documentation, the vast majority has come from our favorite cpuid reference (sandpile.org), but I'll try to track down anything else that is relevant.

[Dr-Noob]

Sounds good to me!