> All used CPUs have a MMU, but it is not used due to performance reasons as 
> the developers state.
> Someone threw a number into the discussion and said enabling the MMU would 
> cause performance losses of about 30-40 percent, thus if we >switch to Linux 
> at all it would have to be ucLinux.

Is it disabled in the proprietary operating system. It is an misnomer
that MMU Slows down the embedded application.
Certainly debatable.

The key issue is do you have enough memory to turn on the MMU. Say an
4K Memory to 256M Memory the requirements are
different.

When you say that the CPU has MMU, It would be wise to add memory to
the device and turn on MMU.

> Unfortunatley I don't have enough experience in low-level programming, so I 
> don't know if this is true, but I would like to know!
> As far as I understand the scope of your project are systems that simply 
> don't have a MMU due to hardware design reasons.
> Is this correct?
This is the second reason to turn on MMU. Simply killing to let an
novice into application/system based low level memory
binding. Always the NAND or NOR Flash, example, can be used along side jffs2.

> Of course I COULD run it on systems with a disabled MMU, but why should I if 
> my processor has the luxury of a MMU and I already payed for it? Is the 
> trade-off for hardware supported virtual memory (=enabling the MMU) really 
> that significant as mentioned above? What are your experiences?
This is the third reason. When you say the mmu is being paid for, Why
not? add some more memory.
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