Re: uC for Indirect Execution



Ulf Samuelsson wrote:
"rektide" <rektide@xxxxxxxxx> skrev i meddelandet news:1147392869.617901.143150@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hey everyone,

I'm looking at starting a new uClinux platform for myself sometime in
the not-too-far-future. I've got a couple favorites I'd like to play
with, namely the Blackfin BF561 and the Lpc3180. However, I'm kind of
worried about what code I can execute: if i recall correctly, neither
of these architectures (ARM9 and blackfin) can execute code indirectly,
can run code from ram. I presume this is a restriction of their
Harvard architetures.

Where can you store code for these architectures?
What are fast & low powered micros that can execute code from memory?

I could be dead wrong, if so, please except my graceful apology.
-Rektide.


Why uCLinux for an ARM9 with an MMU.

People often run ucLinux in embedded systems even if there is an MMU. An MMU provides two things - flexibility for things like swap space, which is seldom used in embedded systems, and memory protection between processes. In most embedded systems, you have (or should have!) total control over which processes and programs are running, and don't need this sort of protection. MMU's are not free - they often add latency to memory access, and they can greatly increase processes switching overhead, so there are good reasons not to use one even when it is present. Of course, it all depends entirely on your application - there are plenty of good reasons *for* using the MMU as well.

Curious to know why you want to run Linux without any Ethernet nor LCD?

.



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