Re: memory management issue (Re: another regression on Efika)

[Hollis Blanchard]

On Tue, 2007-07-10 at 16:08 +0200, Robert Millan wrote:
> On Tue, Jul 10, 2007 at 12:04:44PM +0200, Jordi Mallach wrote:
> > Hey,
> > 
> > On Wed, Jul 04, 2007, Hollis said:
> > > This problem could be caused by firmware presenting an
> > > incorrect /memory/available property. I would instrument
> > > grub_available_iterate() and heap_init() to confirm.
> > > 
> > > That property lists unclaimed areas of memory, which are free for us to
> > > use as heap. The memory used for firmware itself (including exception
> > > handlers at 0), and the memory used by the loaded ELF file (GRUB), are
> > > missing from /memory/available, so we know not to try to use those
> > > regions for the heap.
> > > 
> > > If that is in fact the problem (which wouldn't surprise me given this
> > > particular firmware's track record), then we'll have to add some
> > > hardcoded hack particularly for Efika in grub_machine_init(), bypassing
> > > the more general code we have now.
> > 
> > I'm afraid there must be more to this.
> > 
> > [...]
> > 
> > When the package was later on updated to a CVS snapshot of 20070505,
> > GRUB started dropping me to OF at boot time. On Saturday, Robert helped
> > me track this regression down to this same commit. After reverting and
> > regenerating grub, I'm happy to report that for the first time my
> > Powerbook G4 laptop was able to boot with me pressing no keys at all,
> > using GRUB.

So you're talking about a completely different failure mode, correct?

> > In short, whatever is causing these crashes is not only an Efika issue.
> > I suspect Apple, or Apple powerbooks at least, are also affected. I got
> > Sjoerd to try this on his powerbook, and he confirms this fixes for him.
> > Paul also tried, with the same results. Not all the powerbooks are the
> > very same model, there are different model revisions involved.
> 
> The error Jordi was seeing before reverting your commits was very similar to
> what I get on my Efika (something like "claim failed").
> 
> Hollis, do you still think this is a firmware bug?

Could somebody please debug it and report back if it is really a GRUB
issue? It could be as simple as adjusting the link address, or it could
mean instrumenting grub_available_iterate() and checking that output
with the contents of /memory/available.

-Hollis