Running MMU-less Linux on ARM Cortex-R4

Question

I'm using ARM Cortex-R4 for my system. It has a Memory Protection Unit instead of a Memory Management Unit. Effectively, this means that there's dedicated hardware for memory protection but that there's a one-to-one mapping between physical and virtual addresses. I'm a little confused about which Linux I should go for - standard Linux kernel with MMU disabled or uCLinux.

On ARM's evaluation board, I have run the standard kernel compiled with MMU disabled. I used the cramfs filesystem which is available on the official ARM website. After the kernel boots up, I'm in the shell, but I couldn't do much experimentation as I found that, most of the time, the shell stops responding (particularly when I press "tab" for auto-completion).

So I'm still not sure whether the MMU-less kernel should run smoothly if I use the correct filesystem. Also, which distro (buildroot?) should I use for the no-VM Linux?

Any idea or suggestion is welcome.

Answer 1

It's been more than 2 years since I asked this question. Now is the time I should write what I found for myself.

ucLinux was a project forked from the Linux kernel long back with the aim to develop Kernel for MMU less systems. However, after a certain while, it was merged to the parent Linux branch. So, today there doesn't exist any active ucLinux distribution.

So, if you disable MMU from the mainline kernel configuration, you'll get an MMU-less version. In fact, now there are configuration options provided in the kernel itself whereby a user can specify the memory layout and the access permissions.

Cheers!