[Debian-coldfire-devel] Current Status?

[Wouter Verhelst]

On Tue, Sep 25, 2007 at 06:33:45PM +0200, Carsten Schlote wrote:
> Hi,
> 
> I'm going to use the latest Coldfires (with MMU) for our projects. The
> is a 2.6.10 kernel at least available from FreeScale and some
> toolchain from CodeSourcery. The 'ltib' tool allows for building some
> rootfs.

Yes, that's what I've been using for now.

Note that there are also some bugs in ltib; e.g., I still haven't been
able to create a native compiler; it doesn't even build if I try to
include a compiler in my ltib image.

> While this is all fine, I'd like to see some distribution with binary
> packages precompiled. Shouldn't be that difficult, as the M68k ABI is
> stable for decades, and also works fine with Coldfires.

Having precompiled coldfire-specific packages isn't hard, indeed; in
fact, I could theoretically set that up tomorrow. It's just that that's
not what I've been aiming for.

> If the is project is still active,

We are, to some extent. I'm the only person who's been working on this
so far, and I've slowly come to the conclusion that all this currently
is a bit out of my league -- at least the things I've been trying to do:
modify the toolchain to no longer emit instructions that aren't
supported by the coldfire, while at the same time being able to run on
classic m68k machines, too.

That's a bit harder than it sounds: first, there's one instruction that
exists on coldfire but not on m68k; second, there are some instructions
that behave slightly different (so far I've found FMOVEM and
incrementing or decrementing addressing modes in byte context on
register A7)

> I'd like to contribute over time:
> * Basic kernels for MCF 547x/548x/5445x CPUs
>   It should be possible to pass platform Ids to the kernel init, so that
>   a single image might fit the handfull of MMU enabled Coldfire boards.
> * A generic M68k GCC compiler targeted to Coldfire code generation.
> * Updates for glibc and native linux threading stuff

That'd be cool. There's already someone working on adding TLS support to
glibc; you might want to coordinate with him.

As for the kernel: it was previously suggested that we write some
emulation layer for the missing opcodes on coldfire, so that we could
start using coldfire processors "right away". I didn't do that, because
I know even less about kernel internals and opcode emulation than I do
about compilers and toolchains; but it'd be cool if someone (you, if you
want to) were to help there. After fighting with gcc on my own for so
long, I think I can now safely say that modifying the kernel will be far
easier for someone familiar with it.

> So what is the current status?

What's in subversion. I know, that isn't much, and what's there is
incomplete and already outdated; but I had to do this in my spare time,
and for now I've been mostly pouring over documentation, really.

It'd be cool if there were at least one other person to bounce ideas off
of, but I haven't even had that.

-- 
<Lo-lan-do> Home is where you have to wash the dishes.
  -- #debian-devel, Freenode, 2004-09-22