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

[Daniel Röhrig]

Hey Samuel,

no problem. We changed the offsets and some other stuff in the linker 
script and it's working. The MMU that is. That's where we stopped last 
week.

Thanks for your help!

Regards
Daniel



On 19.07.2012 16:12, Samuel Hitz wrote:
> 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
> to
> 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?
>
> cheers,
>
> Samuel
>
> On Wed, Jul 18, 2012 at 2:54 PM, Daniel Röhrig
> <daniel.roehrig at mailbox.tu-berlin.de
> <mailto: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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