GDB Stubs for PowerPC BSP with old-exceptions

[Robert S. Grimes]

Hi Till,

Sorry for the delay, but you just missed me before a weekend away from work!

Thanks, your comments should prove very useful; I think they're just
what I needed to guide me.

Take care,
-Bob

Till Straumann wrote:
> Robert S. Grimes wrote:
>> Hi Till,
>>
>> Thanks for the response.  Perhaps you misunderstood me, but I
>> certainly wasn't expecting you to support an old standard!  I was
>> envisioning me doing the work, either way...Anyway, Joel has
>> suggested I do the same, for similar reasons.  Given that I've always
>> felt the new model would be better, it seems I've enough good reasons
>> for changing what already works.  Only problem is that I don't have
>> any information about the differences between old and new.
>> Do you or anyone else know where I should look?
> Dunno other than in the obvious places (relevant new/old source
> directories)
> and in a BSP that uses 'new'.
>
> Ideally, you can just use code from the 'vectors' subdirectory of the
> 'powerpc/shared' directory (look at the 'psim' BSP). This works
> for the 60x/750/74xx CPUs. I don't know if you would need modifications
> for the 405 - I'm not familiar with that one.
>
> In any case *do not* copy from powerpc/shared/vectors and create
> a modified version in your 'vectors' subdirectory. This has been very
> bad practice in the past and lead to a bunch of hard to maintain
> variants of code. Due to the low-level nature of exception handling
> there has to be assembly code. We don't want a jungle of variants
> of this code. Don't do it. Please.
>
> If you have to deviate from the 'shared' implementation then think
> about adding run-time tests or (if you have to) compile-time conditionals
> (#ifdef) to the 'shared' implementation so that only a single
> implementation needs to be maintained.
>
> Your Makefile then uses the code from the 'shared' area (ugly, I know;
> there should really be a library)
>
> HTH
> -- Till
>> Or at the very least, suggest one or two good example PowerPC BSPs
>> that implement the new exception model?
>>
>> Thanks!
>> -Bob
>
>