Johan Borkhuis wrote:
Robert Schwebel wrote:
You'll probably have no luck with ARCH=ppc, our port runs with
ARCH=powerpc (and still has some crude hacks inside).
I am in the same situation: I have a board (MVME3100, PPC8540) that uses
the ARCH=ppc, but I have some strict realtime requirements. As far as I
understand from the discussions on this list (and on other places) the
ARCH=ppc will be dropped in favor of ARCH=powerpc, and the -rt patch
will not support the ppc-architecture.
Not dropped but almost frozen. Already today there is little interest in
maintaining the ppc tree. And for real-time preemption and the
high-resolution timers the generic IRQ and timer layer seems now
mandatory, which is not available for ppc. What is mainly missing for
PowerPC is the support of clock events to get the high-resolution timers
working.
Pengutronix has a temporary solution for that. See Robert's mail:
http://www.mail-archive.com/linux-rt-users@xxxxxxxxxxxxxxx/msg00343.html
But before I start working on the powerpc-version of the BSP I would
like to know how stable the patch runs on powerpc (and specifically on
ppc85xx), and how good the realtime performance of the patch is on
powerpc. Are there any (recent) performance measurements available for
the patch on a powerpc platform?
I think MPC 85xx is well supported and in arch/powerpc/configs there are
already a few MPC85xx boards available.
Also a question that is not directly related to this list, but maybe
someone can help me with it. Is there some information available on
porting a BSP from ppc to powerpc? I was not able to find information on
this except for the fact that the ppc architecture will be dropped, but
no information on what impact this has on a BSP.
Unfortunately, porting takes some effort, especially because of the
mandatory Open Firmware flattened device tree (DTF). Please read
Documentation/powerpc/booting-without-of.txt for further information.
But there are already examples for the MPC85xx. There are more new
things like the generic IRQ and timer layer, but that should be already
available for your boards. For more details, please ask on the
linuxppc-embedded ML.
Wolfgang.
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