Re: Question about SMP support for ARM

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

On 08/12/2013 01:28 PM, Chen Baozi wrote:
> On Mon, Aug 12, 2013 at 01:24:40PM +0100, Julien Grall wrote:
>> On 08/12/2013 01:14 PM, Chen Baozi wrote:
>>> Hi Ian & Julien,
>>
>> Hi,
>>
>>> It seems that Xen for ARM is not support SMP boot by default since "max_phys_cpus" is not set?
>>
>> max_phys_cpus allows use to restrict the number of cpus handled by Xen.
>> It's only used to set NR_CPUS. If the former is not set, Xen will use
>> 128 as default value (see include/asm-arm/config.h).
> 
> Thanks.
> 
> Then I think I need to find out why the log says:
> 
> Waiting for 0 other CPUs to be ready
> ...
> Brought up 1 CPUs
> 
> since I do have got 2 cores on OMAP5 and added "kick cpu" codes to
> mode_switch.S next.

Xen uses the device tree to know the real number of cpus.

You should have a node cpus similar to :

cpus {
   cpu@0 {
     device_type = "cpu";
     reg = "0";
   };
   cpu@1 {
     device_type = "cpu";
     reg = "1";
   };
};

Cheers,

-- 
Julien Grall