--- Jared Momose <jpmomose@hotmail.com> wrote:

> Kamal,
> 
> > > >Without translation, you are doomed some nasty
> page
> > > swapping madness. You
> > > >might be able to minimize it by attempting to
> > > locate your binaries to
> > > >different addresses such that concurrently
> running
> > > binaries occupy different
> > > >sections of your address space, but you still
> have
> > > severe limitations
> >
> >Not a problem if you consider that:-
> >(1) there is no swap device
> 
> On this processor, since a "virtual" address can
> only be backed by a single 
> physical address (realize that in this hypothetical
> system, VA would have to 
> be the same as PA), you will need to find a way to
> juggle the contents of 
> the page being addressed.
> 
if we say VA=PA and just place the kernel and requried
binaries at different locations -will that work?

> > > >(multiple instances of the same programe, i.e.
> > > getty, anything multiuser,
> > > >fork needs to be reworked?!). Personally, I
> have
> >
> >do we need getty() on a dsp?
> 
> The issue I presented was that of executing multiple
> instances of the same 
> binary. The problem is that both contend for the
> same address space for 
> data/bss, and will require some funky page swapping
> code to mitigate the two 
> instances.
> 
Yeah -I understood your original pt. I meant, its a
really small piece of hw that will have very few apps
running on it (most likely no more than 1 instance of
each app).

> > > concluded that although it
> > > >may be possible, the result would be terribly
> > > inefficient and not very
> > > >useful for anything academic or commercial.
> > > >
> > >
> >uclinux is the modified version of linux that is
> >commercially used.
> 
> The paradigm used by ucLinux to handle processes is
> very different than 
> Linux. If someone was clever and did port the Linux
> kernel to the Blackfin, 
> including fork() and the ablilty to execute N
> instances of an arbitrary elf, 
> I believe my statement would stand.
> 

Can we emulate virtual to phys translations using s/w?
It will slow things down, but will still be usable. I
mean, assume that every address space resides in a
contiguous block of memory and use a translation
scheme that translates only base addresses.

regards
-kamal


=====
------------------------------------------------------------
Kamal R. Prasad
UNIX systems consultant 
kamalp@acm.org

In theory, there is no difference between theory and practice. In practice, there is:-).
------------------------------------------------------------

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