Re: [ppc patch] grub-mkimage

[Hollis Blanchard]

On Dec 3, 2004, at 10:10 AM, Marco Gerards wrote:
> > > AS Hollis said, I'm working on the relocator for PPC at the moment.
> > > It is quite easy, but PPC_REL24 is a bit more complex.  It is used 
> > > for
> > > relative jumps.  That means the module should be loaded close to
> > > grubof, which IMHO really sucks...
> >
> > 24-bit offsets give you a 16 MiB range, is that really a problem?
>
> The modules are loaded into the free memory of grubof.  And grubof is
> loaded to where it is linked, IIRC.  So I think that would cause
> problems. :)

I don't understand this. By "free memory of grubof" do you mean the 
heap? Right now, grubof is linked and loaded at 0x200000 (size is 
~100KiB right now), and uses memory from 0x4000 to 0x200000 as heap 
space. That means the heap is well within the 16MiB 24-bit offset 
range.

Above grubof, we don't have much to worry about (on any system I know 
of) until 0x400000, which leaves about 1.5 MiB of totally unused space 
just above us. That space also falls well within the 24-bit offset 
range.

So why is there a problem finding a place to put modules that's close 
to grubof?

-Hollis