ARM and x86 on the same system?

[DiggsMcGee]

What if you had a system that utilized both an ARM and x86 processor on the same board? Then you could run applications on either instruction set by passing them through the OS (which would be made to handle this sort of thing) on to the CPU that it needs to run? Everything else is just an interface, right? So graphics cards, USB devices, etc. would act as usual, with the OS and maybe a third chip on the motherboard directing traffic to and from each CPU...

[Arika]

In theory it could run fine, but it's such a niche use case that it would never happen or would be hyper expensive if it did

[AbydosOne]

5 minutes ago, DiggsMcGee said:

What if you had a system that utilized both an ARM and x86 processor on the same board? Then you could run applications on either instruction set by passing them through the OS (which would be made to handle this sort of thing) on to the CPU that it needs to run? Everything else is just an interface, right? So graphics cards, USB devices, etc. would act as usual, with the OS and maybe a third chip on the motherboard directing traffic to and from each CPU...

The PS4 has both an x86 and ARM system in it; one handles gaming, and the other handles connected standby (so it can download games/updates when it's asleep). However, AFAIK, these don't operate at the same time, even if they share the same memory/storage. The PS4 OS is tailored specifically for this.

 

Because the instruction sets are different, you'd have a really hard time operating them simultaneously, without some sort of Java-like universal VM on top of it all, translating universal instructions into whatever core it's being run on at that moment (which would be a huge performance hit).

 

You could perhaps use the other instruction set as a co-processor (a la early Xeon Phi or QNAP Mustang), but then you loose much of the benefit of being tightly integrated when you do that.

[svmlegacy]

21 minutes ago, DiggsMcGee said:

What if you had a system that utilized both an ARM and x86 processor on the same board? Then you could run applications on either instruction set by passing them through the OS (which would be made to handle this sort of thing) on to the CPU that it needs to run? Everything else is just an interface, right? So graphics cards, USB devices, etc. would act as usual, with the OS and maybe a third chip on the motherboard directing traffic to and from each CPU...

If you have a modern CPU, this is already the case. The Intel Management Engine and AMD PSP run on an integrated ARM chip on the CPU. Of course, it's invisible to the OS.

[AbydosOne]

4 minutes ago, svmlegacy said:

Intel Management Engine

Near as I can tell, IME is still x86 (I mean, why would Intel license ARM into every one of their chips when they already own a processor architecture?)

[svmlegacy]

2 minutes ago, AbydosOne said:

Near as I can tell, IME is still x86 (I mean, why would Intel license ARM into every one of their chips when they already own a processor architecture?)

You might be right, but the PSP appears to include ARM:

https://www.extremetech.com/computing/292722-amds-secure-processor-firmware-is-now-explorable-thanks-to-new-tool

It seems rather silly to run simplistic software on a CISC instruction set, when RISC could achieve the same result with less silicon and power dissipation.

From my reading, at least the modern Intel CPU's use a Quark based core, which makes a lot of sense for Intel (Super basic x86 core.)

[DiggsMcGee]

Thanks for the replies!

 

I guess my thought was a laptop that runs an ARM processor most of the time (for power conservation) and is able to run some applications on a more powerful chip (or simply a chip it needs) in order to do video editing, gaming, or high power processing.

 

Thanks again!

[mariushm]

The AMD processors also have an ARM core, for security reasons.

 

Anyway, even if you could get it working, the application would not be able to switch between using the arm and the x86 cores, due to different instruction sets. Then you'd have all kinds of issues with little endian vs big endian, exchanging data between practically two computers...

[WereCatf]

I guess no one in this thread has heard of e.g. Intel's upcoming Alder Lake CPUs, which will sport both x86 - and ARM - cores.

 

In embedded systems, it has already been done years ago, like e.g. I have a cable-modem that uses Intel's Puma - arch and has both x86 - and ARM - cores, which communicate over a virtual internal Ethernet-network.