Re: [Xen-devel] [PATCH RFC 12/35] ARM64: Initialization of cpu_logical_map(0)

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Stefano,

On 05/02/2015 18:26, Stefano Stabellini wrote:
> On Wed, 4 Feb 2015, parth.dixit@xxxxxxxxxx wrote:
> > From: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
> >
> > Initialization of cpu_logical_map(0) before acpi_boot_init()
> >
> > Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> > Signed-off-by: Naresh Bhat <Naresh.Bhat@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/setup.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >
> > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> > index 3531d47..569b2da 100644
> > --- a/xen/arch/arm/setup.c
> > +++ b/xen/arch/arm/setup.c
> > @@ -47,6 +47,7 @@
> >   #include <xsm/xsm.h>
> >   #include <xen/acpi.h>
> >   #include <asm/acpi.h>
> > +#include <asm-arm/cputype.h>
> >
> >   struct bootinfo __initdata bootinfo;
> >
> > @@ -749,6 +750,10 @@ void __init start_xen(unsigned long boot_phys_offset,
> >
> >   #if defined(CONFIG_ACPI) && defined(CONFIG_ARM_64)
> >       acpi_boot_table_init();
> > +
> > +    /* Get the boot CPU's MPIDR before cpu logical map is built */
> > +    cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
> > +
> >       acpi_boot_init();
> >   #endif
> Isn't the current cpu_logical_map initialization in smp_init_cpus()
> enough?  If you want to initialize cpu_logical_map earlier, you need to
> move the initialization earlier, removing the old one: we cannot have
> two places where Xen initialize cpu_logical_map(0).
The ACPI is retrieving the CPU in acpi_boot_init (see patch #11). Having 
this patch separate made this code difficult to understand.
Although, I don't see why we can't defer the parsing of the CPU table in 
smp_init_cpu().
FWIW, it's where we get CPU from the DT.

Regards,

--
Julien Grall

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