Re: Port amigappc

[Frank Wille <frank%phoenix.owl.de@localhost>]

Ignatios Souvatzis wrote:

On 06.01.07 10:54:52 you wrote:

>> Maybe implement a stub near the exception address space, which does
>> something like:
>> 
>> s_trap:
>>    bl  s_trap2
>>    .long   s_trap_kernel   # R_PPC_ADDR32 reloc
>> s_trap2:
>>    mflr    r11
>>    lwz r11,0(r11)
>>    mtlr    r11
>>    blr
> 
> Uh, no. This creates stalls waiting for the memory  read.

As the "bla" restrictions force the stub-code being in slow Chip-RAM there
will be many stalls anyway. ;)

Mapping a piece of of Fast-RAM to 0xffff0000 and using a high-vector
configuration (as under AmigaOS+PowerUp/WarpOS) would be much nicer, but I'm
still not sure how to do that...


> There's a load high (or was it or to high) instruction in the PPC
> instruction set, and you can tell the assembler/linker to put the
> high part of the address in there. There are examples.

Oh... yes, of course! It's SVR4! I was thinking in PowerOpen-ABI. :)

Ok, but you would choose the stub-solution as well? Then I would need to
define absolute symbols, like ".set s_trap,0x3000", as start-address for the
stub code.


-- 
    _  Frank Wille (frank%phoenix.owl.de@localhost)
 _ //  http://sun.hasenbraten.de/~frank/
 \X/   Phx @ #AmigaGer