From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH RFC 12/35] ARM64: Initialization of
	cpu_logical_map(0)
Date: Wed, 11 Feb 2015 13:09:32 +0800
Message-ID: <54DAE40C.10808@linaro.org>
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>, parth.dixit@linaro.org
Cc: ian.campbell@citrix.com, Naresh Bhat <naresh.bhat@linaro.org>, tim@xen.org, xen-devel@lists.xen.org, stefano.stabellini@citrix.com, Hanjun Guo <hanjun.guo@linaro.org>, jbeulich@suse.com, christoffer.dall@linaro.org
List-Id: xen-devel@lists.xenproject.org

Hi Stefano,

On 05/02/2015 18:26, Stefano Stabellini wrote:
> On Wed, 4 Feb 2015, parth.dixit@linaro.org wrote:
>> From: Naresh Bhat <naresh.bhat@linaro.org>
>>
>> Initialization of cpu_logical_map(0) before acpi_boot_init()
>>
>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
>> Signed-off-by: Naresh Bhat <Naresh.Bhat@linaro.org>
>> ---
>>   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