Linked by Thom Holwerda on Tue 13th Nov 2012 22:24 UTC
AMD "Advanced Micro Devices has hired JPMorgan Chase & Co to explore options, which could include a potential sale, as the chipmaker struggles to find a role in an industry increasingly focused on mobile and away from traditional PCs, according to three sources familiar with the situation." Woah. Bad news for competition in the x86 space.
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RE: What about 64-bit only?
by Neolander on Wed 14th Nov 2012 15:02 UTC in reply to "What about 64-bit only?"
Member since:

If a company bought AMD and lost the rights to the x86 instructions what kind of damage would be done by going 64-bit only? Obviously, most 3rd party Windows consumer applications and the current linux compatibility layer in FreeBSD would be affected, but what about the OSes and the instructions in the CPUs?

Does Windows 64-bit Vista/7/8 have 32-bit code still lingering that would keep them from running on AMD chips? Would we lose instructions like sse or do they have 64-bit versions? Most importantly, would any chips be grandfathered in so while new chips would lose 32-bit instructions, the new company could still produce the current line of CPUs while they make the transition?

I would see two problems with that:
1/AMD64 processors start in x86 compatibility mode as an architectural decision, so removing x86 support would effectively imply creating a new incompatible processor architecture (similarly to what was done in IA-64... and it bombed)
2/Even with fully 64-bit operating systems, most user software is still 32-bit. An x86 compatibility mode would thus be necessary in order to execute it.

Edited 2012-11-14 15:06 UTC

Reply Parent Score: 1

RE[2]: What about 64-bit only?
by zima on Thu 15th Nov 2012 06:22 in reply to "RE: What about 64-bit only?"
zima Member since:

Plus, isn't amd64 effectively a superset of x86? Meaning you can't really implement the former without major parts of the latter?

Reply Parent Score: 2

Neolander Member since:

Plus, isn't amd64 effectively a superset of x86? Meaning you can't really implement the former without major parts of the latter?

Yeah, AMD64 also follows a logic that's very similar to that of x68, but I don't know if Intel's license/patents/whatever prevents people from doing what they want with x86 go this far.

Edited 2012-11-15 07:30 UTC

Reply Parent Score: 1

twitterfire Member since:

Data is 64 bit, instructions can use 16, 32 or 64 bits.
For example:

mov ah, bh //16 bit

mov ax, bx //32 bit

mov rax, rbx // 64 bit

Intel patents cover instruction set so you can't have x64 only cpus without infringing Intel's patents.

So that's why hardware patents are as bad as software patents because they hinder competition.

Reply Parent Score: 2