Everything a MMU does?

[whm1974]

I've reading about Memory Management Units which many Microprocessors didn't start out having them along with a FPU, like they have now. Now I know that having a MMU implemented in a Microcomputer with OS support, provides Virtual Memory and Memory Protection. But I am wondering if these things provided in Software /w a MMU?

https://en.wikipedia.org/wiki/Memory_management_unit

 

I can image however that the System will take a performance hit however.

[igormp]

Yes, you cam emulate a MMU in software, but it's painfully slow. Like a thousand times slower (I'm not exaggerating), so it nullifies any benefit of doing so.

 

IIRC, someone tried it with DSLinux in order to have paging, but it was not worth it in the end.

[whm1974]

1 minute ago, igormp said:

Yes, you cam emulate a MMU in software, but it's painfully slow. Like a thousand times slower (I'm not exaggerating), so it nullifies any benefit of doing so.

 

IIRC, someone tried it with DSLinux in order to have paging, but it was not worth it in the end.

Well I knew that FPUs can be emulated in Software to use Linux and other OSes and software that Require a FPU to be installed. But that last time I had a System that uses a Processor without a FPU was way back in ~1994.... Every Computer own since then had FPU...

[igormp]

6 minutes ago, whm1974 said:

Well I knew that FPUs can be emulated in Software to use Linux and other OSes and software that Require a FPU to be installed. But that last time I had a System that uses a Processor without a FPU was way back in ~1994.... Every Computer own since then had FPU...

Many microcontrollers and embedded SoCs don't have neither a FPU nor a MMU (specially some routers). That's why things such as µCLinux exists (and projects built on top of it, such as OpenWRT).