Re: [ECOS] Memory Mapping

[Gary Thomas <gary at mlbassoc dot com>]

Dileep Kumar wrote:
> Hi,
> I am doing a project, which is poritng eCos on MPC8555 processor and I
> am new to eCos. For the porting process I am using MPC8260 as
> baseline.
>
> I go through the code in the file "var_regs.h" under
> -packages\hal\powerpc\mpc8260\v2_0b1\include. I also read reference
> manual which is  MPC8260UM.pdf. I found the some difference in value
> stored in the registers .The value in the reference manual is
> different from the code. Why this difference?
>
> Now I am trying memory mapping .Please tell me how to proceed, and
> please help in my activity.

Try building eCos for an 8260 target, e.g. rattler.  Then see
what files are being used, etc.  You'll find these directories
to be important:
  hal/powerpc/arch
  hal/powerpc/mpc8xxx
  hal/powerpc/rattler

You'll need to create a similar setup for the 85xx and your
particular target:
  hal/powerpc/arch
  hal/powerpc/mpc85xx
  hal/powerpc/xyz

There should be no reason to change anything in hal/powerpc/arch,
only your variant (hal/powerpc/mpc85xx) and target (hal/powerpc/xyz)
Some of things that need changing are simple, others willl be quite
involved.  The PowerPC reference manuals are your guide.

Note that the 8555 is *very* different from the 8260.  The core
is completely different (the 8260 is similar to a 603 whereas
the 8555 is based on the Book-E standard).  There's a lot of
work involved.  Most of the changes will be at the lowest level
and much of it in the [assembly coded] target startup code.
In the case of the 8260 target, this code is in the file
  hal/powerpc/current/src/rattler.S

Once you have the basics setup (start with the simplest, HAL
only configuration), then you'll need to debug it.  This *will*
require a hardware debugger, like a BDI-2000.  Trying to do it
with anything less is bound to fail.

After you have the basic HAL running, then you'll need to update
the various device drivers.  These are also all quite different
from any of the existing targets, so there's a lot more work
there.

You *absolutely* should start from the public CVS tree, not
the 2.0 release (which is now approaching 6 years old).

Finally, feel free to ask questions here on the eCos mailing
lists.  Someone may help (or may not, that's the risk of
public projects).  Please don't send any more private requests
to me (I got multiple pleas today on different addresses).  I
volunteer my time and expertise on this list, but private
email support is only available with a support contract.

--
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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