[Barrelfish-users] Problems with the MMU and a different memory layout

Samuel Hitz samuel.hitz at gmail.com
Thu Jul 19 16:12:40 CEST 2012

Hi Daniel,

Sorry for letting you wait. I'm pretty busy with writing my thesis...

What you say is correct. This should be a mov r1, r2 or mov r1, pc (doesn't
matter). As for your other problem, if you are sure the copying and
expanding stuff is working correctly then the error is probably somewhere
when you create your mappings. Did you change BOOT_STACK_PHYS accordingly
to reflect your memory layout? Otherwise the first mapping fails. I'd
suggest changing the line
and     r2, sp, r3
ldr r2, =0x20000000
anyway, since it's much clearer what you are trying to do.

You should also change the domain permissions back to client, since you
won't get any permission faults otherwise (just an advice for later). What
are you trying to achieve with the code right before activating the MMU?



On Wed, Jul 18, 2012 at 2:54 PM, Daniel Röhrig <
daniel.roehrig at mailbox.tu-berlin.de> wrote:

> Hey Guys,
> we think we might have stumbled upon a little mistake in your arm port
> that still works with the integratorcp boards but will cause problems on
> other boards.
> In the boot.S, Line 140:
> Are you sure you mean "mov r1, r1" and not "mov r1, r2"? mov r1, r1 is a
> nop and section_map will do exactly the same twice. But if you change it
> to mov r1, r2 you really do map the section containing the programm
> counter.
> Regards
> Daniel
> On 16.07.2012 22:39, Daniel Röhrig wrote:
> > Hey guys,
> >
> > we've been trying (rather unsuccessfully) to get Barrelfish up and
> > running on a slightly changed integratorcp board in qemu. The problem
> > is, we don't have memory at 0x0. Our memory starts at 0x20000000. We
> > changed the boot.S to reflect these changes but as soon as we enable the
> > mmu we get an prefetch abortion. And honestly we are running out of
> > ideas why this keeps happening. We stepped through the whole process in
> > gdb but everything seems fine.
> >
> > We would be very happy if somebody could take a look at our boot.S and
> > point out the obvious mistake that we can't find.
> > Here's the link:
> >
> > http://pastebin.com/KDE19qdu
> >
> > Thanks and cheers
> > Daniel
> >
> > _______________________________________________
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> > Barrelfish-users at lists.inf.ethz.ch
> > https://lists.inf.ethz.ch/mailman/listinfo/barrelfish-users
> >
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