Re: [Xen-devel] [PATCH RFC] fix sun6i crash on setup_pagetables

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2013-07-24 at 19:33 +0100, Julien Grall wrote:
> On 07/24/2013 01:14 PM, Bamvor Jian Zhang wrote:
> > this patch move set_processor_id in front of setup_pagetables
> > in order to fix crash when calling this_cpu in that functions.
> > the HPTIDR is unknown value according to ARM ARM 7AR(DDI0406C),
> > B4-1598. we should use it before using it.
> > 
> > but i do not know why other board like arndale board. should
> > bootloader write this register?
> 
> On the Arndale, by default the value of HPTIDR is equal to 0. So it
> works without any issue.

Right, but strictly the register is undefined reset on reset.

The bootloader cannot initialise it because the meaning is entirely OS
specific.

> During the afternoon, I have noticed this error and send a similar
> patch few minutes ago. I also moved percpu_init_areas earlier.

Right, I think this makes sense.

I suppose I should just take your (Julien's) version of this patch?

> For the next patches, could you add the appropriate people? It will
> avoid to loose your patch with the other mail of the mailing list :).

Yes please!

> 
> > 
> > Signed-off-by: Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> > ---
> >  xen/arch/arm/setup.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> > index 2f9fdc8..3bf1b40 100644
> > --- a/xen/arch/arm/setup.c
> > +++ b/xen/arch/arm/setup.c
> > @@ -437,6 +437,7 @@ void __init start_xen(unsigned long boot_phys_offset,
> >      cpus = smp_get_max_cpus();
> >      cmdline_parse(device_tree_bootargs(device_tree_flattened));
> >  
> > +    set_processor_id(0); /* needed early, for this_cpu() */
> >      setup_pagetables(boot_phys_offset, get_xen_paddr());
> >      setup_mm(fdt_paddr, fdt_size);
> >  
> > @@ -459,7 +460,6 @@ void __init start_xen(unsigned long boot_phys_offset,
> >      make_cpus_ready(cpus, boot_phys_offset);
> >  
> >      percpu_init_areas();
> 
> I think you can also move percpu_init_areas earlier.
> 
> > -    set_processor_id(0); /* needed early, for smp_processor_id() */
> >      set_current((struct vcpu *)0xfffff000); /* debug sanity */
> >      idle_vcpu[0] = current;
> >  
> > 
> 



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