> > The worst thing is they removed the MMU :-(
>
> No, the basic 68000 DOES NOT have MMU, thus they removed nothing.
> The first CPU in 68K series with internal MMU is 68030.
>
True, but the 68020 (and 68010 AFAIR) is also designed to work with an
external MMU. Although the MMU chip for the 68010 was strange.
> Now I wonder why you would want to have a MMU in an embedded
> application system.. I do think the MMU is something for
> multi-user time-shared systems, and not space-constrained,
> and possibly power-constrained gadgets.
> (Sure it would be "cool" to have Linux running at my wrist-
> watch and show the time thru X, but why I should burn all
> those wats of power ? Just to keep my wrist warm ?)
Look at the docs of recent embedded RISC chips. Some MMU can
operate in two modes of operations:
- one is to define which areas of memory are
cacheable/write-through/write-back attributes. In the era of on chip
caches even for embedded processors, it is necessary.
- the other mode is a normal MMU mode (paging) for PDA...
And do not forget that keeping instructions and data in the cache
actually saves power, since in these chips very often the I/O buffers
dissipate a significant proportion of the power when they are enabled.
Gabriel
P.S: I now think we should stop this thread or make it private, it is not
about kernel development.