[uClinux-dev] about nommu or mmu

David McCullough davidm at snapgear.com
Wed Mar 19 03:32:57 EST 2003

Jivin John Williams lays it down ...
> ChangDa Tong wrote:
> >I mean if more and more cpu used in the embedded device have a mmu,
> >could uclinux have less usage? Could the nommu cpu's is used less in the
> >near future? Maybe this affect  the spreadness of uclinux. Could anyone
> >show some facts that nommu processor is hard to be repleace the nommu
> >ones?
> An interesting question, which could be subtitled "The future of uClinux".

There was a uCdot poll for this topic that be found at:


Consensus (of the few votes) is that no-mmu platforms will be around
for a while.

> To get the ball rolling, you might speculate that uClinux will just go 
> deeper and deeper embedded.  At the coal face it will always be the 
> struggle of getting the necessary performance from the cheapest piece of 
> hardware that will do the job.

I would agree.

> When the processors used in a network router (like SnapGear's stuff) can 
> "afford" an MMU, then they would probably upgrade to regular linux.

We already have a number of routers using MMU systems.  Some use AMD x86
CPU's while others are running Hitachi SH4 cpus.  We have new platforms
underway for even more platforms.

> However, by that time, even smaller, cheaper and faster no-mmu 
> processors will exist, and they will be embedded in your internet-ready 
> toaster.  Then, by the time the toaster manufacturer upgrades to proper 
> linux, maybe you'll run uClinux in your internet enabled wrist watch, or 
> the microchip embedded in your skull that reminds you to take out the 
> garbage and feed the cat.  I can see it now, tattoos reading "uClinux 
> inside"!
> Of course I'm being a bit silly, but the "ubiquitous computing" folks 
> will need an OS, and uClinux might well be it.

I think this is a fair comment.  MMU's take up space and if you don't
need them then you don't want to pay the cost (no matter how small ;-)


David McCullough:    Ph: +61 7 3435 2815  http://www.SnapGear.com
davidm at snapgear.com  Fx: +61 7 3891 3630  Custom Embedded Solutions + Security

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