Re: Building for custom 68k or ColdFire board without OS?

[Toralf Lund <toralf at procaptura dot com>]

Mark Powell wrote:

> We use the development environment you are proposing and it works 
> extremely well.

Sounds good.

Do you use the assembler at all? How well does it work?

The thing is, I actually tried to set up a gcc cross compiler once 
before, but it didn't quite work out right, and one of the problems was 
that the assembler (gas) had somewhat limited functionality. I think I 
followed the wrong track back then, though, as I tried to create a setup 
that would read and write OS-9 format objects and libs, so that I might 
use the existing clib etc., and also support some legacy OS-9 software. 
Because of that, I started off with a distribution with partial OS-9 
support that was based on a fairly old (2.6 or so) gcc version. The fact 
that the gcc was so old may have contributed to the problems, and I 
think now that building new libs and updating the loader for a new exec 
format is probably easier than tweaking gcc to work with the old 
environment (and I don't really care about the OS-9 apps; they are more 
or less obsolete anyway.)

> I built a cross tool-chain that supports the m68k family and ColdFire 
> (I built it on Intel/Linux, Sparc/Solaris and HPUX hosts) and used 
> that to compile newlib (http://sources.redhat.com/newlib/). Newlib has 
> separate C and math libs.

So newlib, not glibc or similar, is the thing to use for embedded systems?

> I wrote some low-level routines (in C) that newlib calls to do serial 
> port i/o to the UART 

Would that be routines to read or write one character? I have those 
allready...

> and voila we had printf, getchar, scanf etc on a TTY console.

How about "cstart"?

> I then extended the serial i/o driver to use interupts and buffer 
> characters and this provides a sort of background i/o capability for 
> diagnostic menus on the TTY console.
>
> The only thing is, it's not packaged up with an idiots guide that 
> requires no previous knowledge. You should expect to understand the 
> workings of the toolset and how to generate ROMs etc.

I am at least quite familiar with gcc, and I know how to load the code 
onto the current hardware (although I may have to research the new 
output format a bit.)

- Toralf



------
Want more information?  See the CrossGCC FAQ, http://www.objsw.com/CrossGCC/
Want to unsubscribe? Send a note to crossgcc-unsubscribe@sources.redhat.com