[Barrelfish-users] ARM support in barrelfish

Zeus Gómez Marmolejo zeus.gomez at bsc.es
Fri Nov 16 16:01:47 CET 2012

Hi Kornilios,

Following the conversation we had with Mothy early this week, we agreed
that the best platform to support Barrelfish on Gem5 is the Versatile
Express EMM, due to the lack of support of the ELT, as Matt said. Therefore
I'm sending you a patch to apply on top of revision 1081, which is the last
Barrelfish version that boots on Gem5 (Samuel branch).

This has 2 advantages:
1. Gem5 doesn't need to be patched. It works on the last mercurial tip from
today (revision 0fea324c832c). I've written this in the README.
2. We are using the currently supported EMM instead of the old ELT.

>From this, you can proceed with the merge, trying to unify all ARM

I hope it helps!

2012/11/12 Kornilios Kourtis <kornilios.kourtis at inf.ethz.ch>

> Hi Zeus,
> Thanks for your comments! I'm inlining some responses below.
> On Fri, Nov 09, 2012 at 03:28:16PM +0000, Zeus Gómez Marmolejo wrote:
> > Here at ARM we have been working with the ARMv7 and the Gem5 simulator,
> > but we have found many problems. First, the Mercurial tip is not
> > booting in Gem5.  There is currently a mixture between the pandaboard
> > work done (that is working on physical memory 0x80000000) and the Gem5
> > model (starting at 0).
> >
> > The last version that works on Gem5 is the latest revision from Samuel
> > Hitz branch (revision 1081). But note that has to be compiled with a
> > GCC version up or prior to 4.6.1 due to the inline bug of GCC, as
> > Barrelfish code seems to have the 4.6.1 version harcoded in some
> > headers (search for 'inline bug' in Barrelfish code). As far as I know,
> > gcc 4.6.3 is affected by this bug too and is generating incorrect
> > binaries, so this workaround should also include that version too.
> We are aware of these issues, and they were the ones that (partially)
> triggered sending the original mail. Unfortunately we haven't fixed them
> due to limited bandwidth, but we hope to fix them soon.
> > We agreed with Matt to have a Gem5 model of the pandaboard to unify
> > platforms.  First because it would be useful for you as tests could be
> > run both on Gem5 and pandaboard without any change, and second because
> > the current Gem5 board that is being used is the Versatile Express ELT,
> > which has been removed from recent versions of Gem5.
> Having a gem5 pandaboard platform sounds very usefull (as is Matt's
> suggestion of EMM). I'm not sure if it makes sense to have both or just
> one (not sure how much overhead woud that add), but the current platform
> seems not to be the best choice right now.
> cheers,
> Kornilios.
> --
> Kornilios Kourtis

Zeus Gómez Marmolejo
Barcelona Supercomputing Center
PhD student
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