SMP for L4Linux on i.MX6

Adam Lackorzynski adam at os.inf.tu-dresden.de
Sun Oct 19 23:55:16 CEST 2014


On Thu Oct 16, 2014 at 23:33:28 +0300, Uwe Geuder wrote:
> On 13 October 2014 21:19, Adam Lackorzynski <adam at os.inf.tu-dresden.de> wrote:
> >> Does the virtual CPU seen by L4Linux
> >> need to control/use the SCU or is that something made completely transparent
> >> by the virtual cpu offered by L4?
> >
> > User programs, such as L4Linux, have nothing to do with the SCU, i.e. it
> > is completely transparent.
> 
> OK, good.
> 
> So I measured again and could not find any effects whether l4x_cpus=3 is
> present or not.
> 
> Next I looked at the code what l4x_cpus= does. And indeed it does nothing.
> To be more exact all it does is inside #ifdef CONFIG_SMP. You did
> not explicitly say that I should disable that option, but I still concluded I
> should do so to get rid of the build failures. 

CONFIG_SMP must be enabled.

> But as I wrote before, I had not been able to build with that option enabled
> >
> >> Next I looked at our L4Linux configuration and indeed CONFIG_SMP was not
> >> set. However after enabling it the kernel does no longer build:
> >>
> >> arch/arm/mach-imx/built-in.o: In function `imx_smp_prepare':
> >> /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:79: undefined reference to `scu_enable'
> >> /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:79: undefined reference to `scu_enable'
> >> arch/arm/mach-imx/built-in.o: In function `imx_smp_init_cpus':
> >> /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:71: undefined reference to `scu_get_core_count'
> >> arch/arm/mach-imx/built-in.o: In function `v7_secondary_startup':
> >> /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/headsmp.S:33: undefined reference to `v7_invalidate_l1'
> >> /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/headsmp.S:35: undefined reference to `secondary_startup' 
> 
> So if CONFIG_SMP is needed to be selected, how can I solve the build problems?

Are there any build issues when you use an unmodified L4Linux, i.e. one
that does not have any adaptions for imx?



Adam
-- 
Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/



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