Can Intel refuse to sell such license to nVidia or ask for much higher fees than other companies? If nVidia bought one of those companies, would that allow them to produce x86 chips at will?
> Can Intel refuse to sell such license to nVidia or ask for much higher fees than other companies?
Yes. There's no requirement to sell licenses to patents in general. Sometimes (not always) if a patent is included by a government in a standard that government will require the owning company to license it on "Fair, Reasonable, And Non-Discriminatory" terms (FRAND). Most patents, including the x86, x86_64, and various extension patents are not required to be licensed under FRAND terms.
AMD and Intel have a mutual licensing agreement. When Intel patents a new extension, they license it to AMD. Likewise when AMD patents a new extension, the license it to Intel. That's why Intel CPUs use the AMD x86_64 instruction set, AMD CPUs use the Intel AVX 512 vector instructions, etc.
AMD only got one for the 286 because IBM wanted a second source supply for their IBM PC's and things got murky when the i386 came around and AMD needed to compete.
There were some copying and I think they settled with AMD licensing the Intel FSB for $$$ (they switched to DEC Alpha bus protocol when the AMD Athlon 64 bit era came around).
With the AMD 64 they licensed it back to Intel when it became clear that Itanuim was dead as it was so slow and Microsoft forced Intel's hand by releasing a version for Windows Server.
As far as I can remember they would have to buy AMD, VIA or IBM to get a X86 licence. That's just the beginning though as many later patents are also important, but they would likely also be already licensed by these companies (like AMD64 for one). If they could even use the license after a take over.... I don't know.
If AMD got taken over, then they would automatically lose their x86 license, as I believe it is a condition in their cross-licensing agreement. This is why I don't expect AMD to get bought in the near future.
