On Thu, Nov 26, 2020 at 05:46:48PM +0100, Antony Stone wrote:
> On Thursday 26 November 2020 at 17:35:18, Fred wrote:
>
> > I installed arch-test which says i386. I am sure an AMD cpu will run
> > x86 instructions but I don't see how a x86/i386 cpu will run the
> > instructions that AMD presumably added.
>
> i386 is a 32-bit standard.
>
> Any 64-bit CPU (from AMD or Intel, doesn't matter which) can also run 32-bit
> instructions - this appears to be what you are doing on your machine right
> now.
>

> > fred@ragnok:~$ lscpu
> > Architecture:        i686
> > CPU op-mode(s):      32-bit, 64-bit
> > This seems to say I can run 64 bit software.

>
> Indeed, it does.
>
> > Is the i386 version of Devuan only 32bit?
>
> Yes, i386 is a 32-bit standard.
>
> > Else how is 64 bit installed instead? If you want 64 bit you have to
> > install the AMD64 version which means I have to change the MB to one that
> > has an AMD cpu?
>
> No, AMD64 is a 64-bit instruction set definition, common to both AMD and Intel.
>
> https://en.wikipedia.org/wiki/Amd64
>
> > Who took the lid off this can of worms?
>
> It isn't a can of worms, it's just potentially confusing terminology if you
> think that "AMD64" means you have to have a CPU made by AMD.

Historical reasons:

Intel made a 64-bit architecture, the Itanium. It was incompatible with i386.
AMD made a 64-bit architecture which had a 32-bit mode that was compatible
ith i386. And they designed their 64-bit instruction set so that it didn't
involve a huge duplication of hardware between the two versions.

The intel 64-bit instruction set ended up being called IA64.

So the AMD architecture which just expanded i386 ended up being called
AMD64.

And market pressures meant intel ended up making AMD64 processors, which
massively outsold Itania.

-- hendrik

>
>
> Antony.
>
> --
> If you can't find an Open Source solution for it, then it isn't a real problem.
>

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