[U-Boot-Users] [PATCH][FOR 1.3.4] 85xx: Don't move interrupt vector to low memory

[Kumar Gala]

On Aug 6, 2008, at 2:46 PM, Wolfgang Denk wrote:

> In message <20080806193205.GA3975 at ld0162-tx32.am.freescale.net> you  
> wrote:
>>
>> It's hit me before when I foolishly try to load something at address
>> zero -- why do we put u-boot at the end of RAM, and put up with the
>> relocation weirdness, if not to allow loading things at zero?
>
> We want to free as much memory as possible. But low RAM cannot be made
> available on all systems.
>
>>> Well, one reason might be to have identical code for all PPC  
>>> systems ?
>>
>> It's already 85xx-specific code.
>
> Good point. Why don't we factor this out and make it common code for
> all PPC?

Because the relocation is specific to the various interrupt types.   
Book-E will need different code for handing IVPR/IVORs than classic.

>>> Not only 6xx. Actually all PPC.
>>
>> No, not all PPC.  Book-E exceptions are different.
>
> Maybe. But then, these can use exception vectors at low mem, too,
> right?

They can, but it has to be setup.

> For me the chance to have common code (and identical behaviour) for
> all PowerPC processors is much more important that being able to use
> 16 kB additional memory on one specific family of processors.

- k