[uClinux-dev] uClinux on 68000 confusion

David McCullough davidm at snapgear.com
Mon Mar 24 21:59:43 EST 2003


Jivin John Williams lays it down ...
> David McCullough wrote:
> >Jivin Jonathan L Long lays it down ...
> >
> >>I am attempting to put uClinux on my 68000 board. However, I am a bit 
> >>confused about how to compile uClinux for the straight 68000. I have 
> >>downloaded the latest uClinux-dev tarball. There are arch subdirs for 
> >>m68k and m68knommu; what is the difference? Isn't uClinux only for 
> >>systems without an MMU? Also, 
> >
> >
> >uClinux is a set of patches to support systems without an MMU,  it
> >doesn't remove support for systems with an MMU, although you wouldn't be
> >the first to make that assumption :-)
> 
> What are the consequences of just ignoring MMUs and running uClinux 
> instead or regular linux?  Apart from what you lose (virtual memory 
> etc), do you gain anything?


Not really, a similarly configure MMU/no-MMU system will be about the
same size.  The flat format can be smaller than say ELF format,  but
I don't think it would be a deciding factor in choosing  one ofver the
other.  I say if you have an MMU then use it.

Someone a while back was using 2.5 without MMU on an SH4 to give them a
fancy (as in very fancy ;-) bootloader setup.  They couldn't be bothered with
all the MMU stuff at that stage.  So I guess some people do want to do
it.

> The hacker in me shouts "the ability for user code to do whatever it 
> needs to without interference from the kernel!", but then 
> software-engineer me quickly locks hacker-me back in the dungeon! :)

Did he throw away the key ;-)

Cheers,
Davidm

-- 
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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