Re: [Xenomai] Boot failure when CONFIG_XENOMAI is enabled

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On Sat, Mar 28, 2015 at 02:53:03PM +0100, Gilles Chanteperdrix wrote:
> On Sat, Mar 28, 2015 at 08:27:33PM +0800, GP Orcullo wrote:
> > On Sat, Mar 28, 2015 at 7:36 PM, Gilles Chanteperdrix
> > <gilles.chanteperdrix@xenomai.org> wrote:
> > > On Sat, Mar 28, 2015 at 10:51:30AM +0100, Philippe Gerum wrote:
> > >> On 03/28/2015 10:05 AM, GP Orcullo wrote:
> > >> > On Fri, Mar 27, 2015 at 8:12 PM, GP Orcullo <kinsamanka@gmail.com> wrote:
> > >> >> On Fri, Mar 27, 2015 at 6:19 PM, GP Orcullo <kinsamanka@gmail.com> wrote:
> > >> >>> What happens in between the clocksource switch and head domain registration?
> > >> >>>
> > >> >>> [    0.090129] DMA: preallocated 4096 KiB pool for atomic coherent
> > >> >>> allocations
> > >> >>> [    0.095333] Switching to clocksource ipipe_tsc
> > >> >>> [    0.122397] I-pipe: head domain Xenomai registered.
> > >> >>> [    0.124618] Xenomai: hal/arm started.
> > >> >>>
> > >> >>> I'm trying to trace the code to find out where it stops. I tried
> > >> >>> adding printk to to the set and request functions and the code never
> > >> >>> runs when CONFIG_SMP is enabled.
> > >> >>>
> > >> >>> Thanks,
> > >> >>>
> > >> >>> GP Orcullo
> > >> >>
> > >> >> It gets stuck on the call to ipipe_critical_enter:
> > >> >> http://git.xenomai.org/ipipe-gch.git/tree/kernel/ipipe/timer.c?id=ipipe-core-3.10.32-arm-7#n279
> > >> >>
> > >> >> Which then gets stuck on ipipe_send_ipi:
> > >> >> http://git.xenomai.org/ipipe-gch.git/tree/kernel/ipipe/core.c?id=ipipe-core-3.10.32-arm-7#n1533
> > >> >>
> > >> >
> > >> > I've traced the issue to the ipipe_processor_id() function. It returns
> > >> > the value 512 for processor 0. This value comes from cpu node property
> > >> > of the DT file.
> > >> >
> > >> > Changing ipipe_processor_id() to return 0 instead of 512 allows the
> > >> > kernel to boot but it fails the switchtest regression test.
> > >> >
> > >> > Changing the cpu0 reg value on the DT file allows the kernel to boot
> > >> > and pass all the xenomai regression tests but it generates the
> > >> > following warning at boot:
> > >>
> > >> No, this property for armv7 must match MPIDR[23:0], i.e. the physical id
> > >> of the core.
> > >>
> > >> > What's the proper way of fixing this?
> > >> >
> > >>
> > >> By fixing ipipe_processor_id() in the CONFIG_LEGACY case, it's broken.
> > >> It assumes __cpu_logical_map[] is a hw->logical map, but it is actually
> > >> the opposite.
> > >>
> > >> We may have been lucky until now because the physical mapping seems to
> > >> have always matched the logical order on the SMP SoCs people used with
> > >> Xenomai so far, it looks like your A5 core does not follow this order.
> > >
> > > No, cpu_logical_map works both ways, it simply exchanges 0 with
> > > whatever number the boot cpu has
> > > so, since cpu_logical_map[0] == 512 and cpu_logical_map[512] == 0
> > > it should work both ways.
> > > At least, that was true before DT. Now, I find 512 a bit high, are
> > > you sure cpu_logical_map[] is large enough ? Or is it even
> > > initialized with DT ?
> > >
> > > --
> > >                                             Gilles.
> > 
> > cpu_logical_map[] contains these values: {512,1,2,3}
> > 
> > This is the cpu entry:
> > https://github.com/hardkernel/linux/blob/odroidc-3.10.y/arch/arm/boot/dts/meson8b_odroidc.dts#L9-L32
> > 
> > Changing the reg values alters the contents of cpu_logical_map[].
> 
> Actually, the code as it existed should either have worked, or bug
> because 512 is larger than __cpu_logical_map size (the largest of 16
> and NR_CPUS).

This is bugging me, if the kernel does not print a bug in
smp_setup_processor_id, it means that NR_CPUS is sufficiently large,
so larger than 512. How much is the compilation constant
CONFIG_NR_CPUS in your kernel configuration ?

-- 
					    Gilles.