Support for PowerPC e200 cores

[Till Straumann]

FWIW, I strongly recommend to abandon the current
PPC multilib mess. The e500 core is at the UISA-level
still powerpc compatible and that's all gcc cares about.

The mvme3100 BSP I recently added uses an 8540 CPU
and the compiler flags

-mcpu=powerpc -mno-float

which work just fine. I am convinced that we could drastically
reduce the PPC multilib variants.

A new multilib-variant would only be needed if the 8450's
single-precision float APU were to be used.

Currently, the main reason for the many variants is that
rtems' gcc specs map the -mcpu=xxx flags to a corresponding
-DXXX which is tested in rtems libcpu and libbsp code.

However, this can also be achieved by the BSP's
custom/<bsp>.cfg fragment adding -DXXX.  It would even
be better to eliminate this kind of conditional compilation.

-- Till

Joel Sherrill wrote:
> Ralf Corsepius wrote:
>   
>> On Fri, 2008-02-15 at 08:48 -0600, Joel Sherrill wrote:
>>   
>>     
>>> Sebastian Huber wrote:
>>>     
>>>       
>>>> Hi,
>>>> we want to develop a BSP for a MPC5566 evaluation board. It uses a e200
>>>> processor core. My first job is to get the basic tools ready. I am quite
>>>> new in
>>>> this business, so please have mercy with me if I ask to many clumsy
>>>> questions ;-)
>>>>
>>>>       
>>>>         
>>   
>>     
>>> Use the RPMs.  I repeat use the RPMs.  There is normally
>>> no reason to generate a custom compiler.  And this case
>>> is certainly NOT an exception that rule.  The current
>>> powerpc-rtems4.9-gcc includes this in its specs:
>>>
>>>  %{mcpu=8540: -me500}
>>>
>>> So the tools should be OK.
>>>     
>>>       
>> They are not - More precisely, the instruction set is in GCC, but the
>> multilib support is missing.
>>
>> Finally, trying to add it (it's one multilib variant) reveals bugs in
>> GCC -- If it was that easy, I would have posted a patch in response ;)
>>   
>>     
> OK.  I guess it's time to start filing PRs again and seeing
> if Debian or Fedora is holding another lump of unsubmitted
> patches that  look to help.
>
>
> --kpe;
>
>   
>> Ralf
>>
>>
>>
>>
>>   
>>     
>
>
>