Re: [PATCH] xen: arm: ignore CPUs which are not marked available in the DT

[Julien Grall <julien.grall@linaro.org>]

On 24/07/14 11:40, Ian Campbell wrote:
> On Thu, 2014-07-24 at 11:36 +0100, Julien Grall wrote:
>> Hi Ian,
>>
>> On 23/07/14 19:36, Ian Campbell wrote:
>>> On Wed, 2014-07-23 at 18:15 +0100, Julien Grall wrote:
>>>> On 07/23/2014 05:45 PM, Ian Campbell wrote:
>>>>> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>>>>> ---
>>>>>    xen/arch/arm/smpboot.c |    3 +++
>>>>>    1 file changed, 3 insertions(+)
>>>>>
>>>>> diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
>>>>> index cf149da..4b0a738 100644
>>>>> --- a/xen/arch/arm/smpboot.c
>>>>> +++ b/xen/arch/arm/smpboot.c
>>>>> @@ -134,6 +134,9 @@ void __init smp_init_cpus(void)
>>>>>            if ( !dt_device_type_is_equal(cpu, "cpu") )
>>>>>                continue;
>>>>>
>>>>> +        if ( !dt_device_is_available(cpu) )
>>>>> +            continue;
>>>>> +
>>>>
>>>> I can't find a such things on the Linux device tree bindings.
>>>
>>> status is a generic property which is common to all nodes, it comes from
>>> ePAPR.
>>>
>>>>    Do you
>>>> have a use case where CPU are marked disabled?
>>>
>>> I use it locally when booting with models -- it allows me to turn off
>>> cpus in the base .dts file using a wrapper instead of having to edit the
>>> original.
>>
>> I read the ePAPR and the property status on CPU node. AFAIU, the
>> property doesn't have this meaning for a such node.
>>
>> This property means the CPU is in quiescent state and property to bring
>> up the CPU is provides in the device tree node.
>>
>> Section 5.5.2.2:
>>
>> Before starting a client program on the boot cpu, the boot program shall
>> set certain properties in the
>> device tree passed to the client as follows:
>> • Each secondary CPU’s cpu node shall have a status property with a
>> value of “disabled”.
>
> Oh well, it was only a convenience for me anyway.
> Ian

Could we add a property xen,status for debugging (i.e when Xen is 
compiled with debug=y)? So we don't collapse with the actual property if 
someone decide to implement it in the bootloader.

Regards,

-- 
Julien Grall

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