Re: PPC64 mlongcall gcc flag

[Robert Millan <rmh@aybabtu.com>]

On Wed, Nov 05, 2008 at 11:25:15AM -0600, Hollis Blanchard wrote:
> 
> Module memory is allocated by grub_malloc(), but as you can see at
> http://svn.savannah.gnu.org/viewvc/trunk/grub2/kern/ieee1275/init.c?revision=1806&root=grub&view=markup the GRUB heap capped at 4MB (I don't mean size, I mean the end of the heap).

It's not really capped at 4 MB.  It will cap it only when an heuristic tells it
there's still enough room for heap:

    /* Avoid claiming anything above HEAP_MAX_ADDR, if possible. */
    if ((addr < HEAP_MAX_ADDR) &&                                /* if it's too late, don't bother */
        (addr + len > HEAP_MAX_ADDR) &&                                     /* if it wasn't available anyway, don't bother */
        (total + (HEAP_MAX_ADDR - addr) > HEAP_MIN_SIZE))                   /* only limit ourselves when we can afford to */

Argueably, this is not my best piece of code...  today I'd have implemented a
payload relocator (like the one used by loader/i386/pc/multiboot.c) just so we
can happily use everything in /memory/available as heap.

And I'd even advice doing the same for powerpc (sharing code with i386 if
possible).

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."