Re: PowerPC C++ kernel woes.

[Hollis Blanchard]

On Sat, 2005-11-26 at 18:42 -0600, Andrei Warkentin wrote:
> I've been trying to get some C++ running (now that I can print
> "Hello  
> World" from OF, I'd like to move my "Hello World" C++ kernel to  
> PowerPC), but it has been without much success.
> I've finally figured out that there are these small data sections  
> which I was not taking care of in my ld script (sdata, sbss, sdata2,  
> sbss2). 

I'd suggest starting with the system-provided linker script and modify
that as needed, rather than trying to write your own from scratch.

> AFAIK, some default ld-script is  
> used while building GRUB2. Am I correct? Is this the standard ld- 
> script used to be exec-objects under PPCLinux?

Yes, GRUB uses the (unmodified) default linker script (see ld -verbose).

> My other question is one of alignment. Looking at various
> PPC-related  
> ld-scripts I found through Google, a lot seem concerned with
> aligning  
> data/bss by 4 bytes or by 8. Is there any reason for this? AFAIK,
> the  
> default linux one does not care about alignment a whole lot. As far  
> as I understand, PPC can cope with misaligned data in hardware.

Alignment is important to hardware. I have personally dealt with a very
difficult-to-debug problem where the stack was misaligned. Different
PowerPC can fix up different misaligned accesses in hardware, but always
with a performance impact. You should align anything that needs
alignment.

My only other advice is that this is not a good place to ask these
questions. You might try linuxppc-dev or the binutils list.

-Hollis