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FreeBSD or other BSD for no-MMU ARM processor ?

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Gary Corcoran

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Jun 14, 2004, 3:32:09 PM6/14/04
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Does anyone know if there is a port of FreeBSD, or any of the
other BSDs (e.g. NetBSD) for that matter, which will run on an
ARM processor which does NOT have an MMU (Memory Management Unit)?

Thanks,
Gary


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Peter Pentchev

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Jun 15, 2004, 2:28:01 AM6/15/04
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On Mon, Jun 14, 2004 at 03:32:09PM -0400, Gary Corcoran wrote:
>
> Does anyone know if there is a port of FreeBSD, or any of the
> other BSDs (e.g. NetBSD) for that matter, which will run on an
> ARM processor which does NOT have an MMU (Memory Management Unit)?

Your best bet would be http://www.netbsd.org/Ports/
Unfortunately, I'm not too familiar with the ARM line of processors,
so it's not really obvious to me if NetBSD supports architecturs without
MMU's. ISTR that there was a decision very early down the line for
FreeBSD to *not* support anything that didn't have an MMU.. or was that
even earlier, and does it also hold true for other BSD's?

G'luck,
Peter

--
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PGP key: http://people.FreeBSD.org/~roam/roam.key.asc
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If the meanings of 'true' and 'false' were switched, then this sentence wouldn't be false.

Wes Peters

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Jun 15, 2004, 2:16:36 PM6/15/04
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On Monday 14 June 2004 12:32 pm, Gary Corcoran wrote:
> Does anyone know if there is a port of FreeBSD, or any of the
> other BSDs (e.g. NetBSD) for that matter, which will run on an
> ARM processor which does NOT have an MMU (Memory Management Unit)?

No, and there's not likely to be one anytime soon (unless you do it).
NetBSD has ports for a couple of ARM920T designs, which do have an MMU.
(I think they've recently popped a port for the Cogent CSB337, based on the
Atmel chip.)

The general feeling seems to be that without an MMU and the added features
of memory protection it provides, the heavyweight process-oriented UNIX
kernel doesn't really offer much advantage over a lighter-weight solution
like RTEMS or eCos. The uClinux gang disagrees with this assessment,
obviously, so you do have that choice as well.

--
"Where am I, and what am I doing in this handbasket?"

Wes Peters w...@softweyr.com

Gary Corcoran

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Jun 15, 2004, 2:50:35 PM6/15/04
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Wes Peters wrote:

> On Monday 14 June 2004 12:32 pm, Gary Corcoran wrote:
>
>>Does anyone know if there is a port of FreeBSD, or any of the
>>other BSDs (e.g. NetBSD) for that matter, which will run on an
>>ARM processor which does NOT have an MMU (Memory Management Unit)?
>
>
> No, and there's not likely to be one anytime soon (unless you do it).

Thanks for the definitive reply. We don't have enough resources for
our work as it is, so no, we're not going to do it - we need something
already available.

> NetBSD has ports for a couple of ARM920T designs, which do have an MMU.
> (I think they've recently popped a port for the Cogent CSB337, based on the
> Atmel chip.)
>
> The general feeling seems to be that without an MMU and the added features
> of memory protection it provides, the heavyweight process-oriented UNIX
> kernel doesn't really offer much advantage over a lighter-weight solution
> like RTEMS or eCos. The uClinux gang disagrees with this assessment,
> obviously, so you do have that choice as well.

Thanks for the pointers. My boss (and our customer) has mentioned eCos,
so we'll be looking into that. RTEMS I hadn't heard of - I'll have to check
into that too. But since I like, and am somewhat familiar with, *BSD, I
thought I'd ask if that might be an option...

Gary

Bruce R. Montague

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Jun 15, 2004, 3:47:09 PM6/15/04
to

Hi, re:

>>Does anyone know if there is a port of FreeBSD, or any of the
>>other BSDs (e.g. NetBSD) for that matter, which will run on an
>>ARM processor which does NOT have an MMU (Memory Management Unit)?
>

> The general feeling seems to be that without an MMU and the added features
> of memory protection it provides, the heavyweight process-oriented UNIX
> kernel doesn't really offer much advantage over a lighter-weight solution
> like RTEMS or eCos. The uClinux gang disagrees with this assessment,


Another such light-weight embedded C kernel with unmapped ARM support
that seems to be popular lately is microC/OS, sometimes called
uC/OS or "mucos". My _impression_ is that it is a free open source system
but that a number of companies sell support and a number of embedded
companies specialize in getting it past validation suites in vertical
niche markets, etc.. I think it's been used for digital cameras and such.

http://www.accu.org/bookreviews/public/reviews/m/m002257.htm

http://www.cmpbooks.com/product/1057

- bruce

Wes Peters

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Jun 16, 2004, 11:56:16 AM6/16/04
to
On Tuesday 15 June 2004 11:50, Gary Corcoran wrote:
> Wes Peters wrote:
> > On Monday 14 June 2004 12:32 pm, Gary Corcoran wrote:
> >>Does anyone know if there is a port of FreeBSD, or any of the
> >>other BSDs (e.g. NetBSD) for that matter, which will run on an
> >>ARM processor which does NOT have an MMU (Memory Management Unit)?
> >
> > No, and there's not likely to be one anytime soon (unless you do it).
>
> Thanks for the definitive reply. We don't have enough resources for
> our work as it is, so no, we're not going to do it - we need something
> already available.
>
> > NetBSD has ports for a couple of ARM920T designs, which do have an MMU.
> > (I think they've recently popped a port for the Cogent CSB337, based on
> > the Atmel chip.)
> >
> > The general feeling seems to be that without an MMU and the added
> > features of memory protection it provides, the heavyweight
> > process-oriented UNIX kernel doesn't really offer much advantage over a
> > lighter-weight solution like RTEMS or eCos. The uClinux gang disagrees
> > with this assessment, obviously, so you do have that choice as well.
>
> Thanks for the pointers. My boss (and our customer) has mentioned eCos,
> so we'll be looking into that. RTEMS I hadn't heard of - I'll have to
> check into that too. But since I like, and am somewhat familiar with,
> *BSD, I thought I'd ask if that might be an option...

You'll like RTEMS, it's the BSD of RTOSes. The community support is great
and Joel Sherrill, the head honcho there, is very responsive to "customer"
input. OARCorp offers all sorts of contract help as well.

In case you haven't found it (not likely), see: http://www.oarcorp.com/

eCos is also very good, and perhaps a bit more polished due to it's Cygnus
Support and Red Hat parentage. I'm noticing more and more eval boards and
development systems for 32-bit embedded cpus that come with eCos. If
you're looking for a low-cost ARM7 solution, the Atmel EVB40 boards might
be of interest. DigiKey carries the EVB40A, with a 66MHz ARM7TDMI chip
(Ateml AT91R40008), which is directly supported by eCos, see:
http://ecos.sourceware.org/ecos/boards/at91eb40a.html

Both eCos and RTEMS use GCC cross-compilers for devlopment, so you'll be
able to stick with FreeBSD as your workstation platform. In fact, the
coupling between FreeBSD and RTEMS is very close; see /usr/ports/devel/ on
your favorite FreeBSD system, where you will find:

arm-rtems-binutils
i386- -g77
i960- -gcc
m68k- -gdb
mips- -objc
powerpc-
sh-
sparc-

Installing the arm binutils (linker, assembler, etc), gcc and gdb ports will
give you a complete RTEMS-arm development environment on your FreeBSD
system with a minimum of fuss and bother. The other two ports will provide
you with a Fortran-77 and Objective-C compiler, if you need those. Am I
making your choice any easier? ;^)

Please let me know how your project goes.

--

Where am I, and what am I doing in this handbasket?

Wes Peters w...@softweyr.com

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