Re: [Xen-devel] [PATCH 3/7] xen/arm: Initialize correctly IRQ routing

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 09/09/2013 02:17 PM, Ian Campbell wrote:
> On Fri, 2013-08-30 at 14:30 +0100, Julien Grall wrote:
>> When Xen initialize the GIC distributor, we need to route all the IRQs to
>> the boot CPU. The CPU ID can differ between Xen and the GIC.
>>
>> When ITARGETSR0 is read, each field will return a value that corresponds
>> only to the processor reading the register.
> 
> This trick is used a few times in this series, is it really the best way
> to figure this out?
> Not in some ID register or in DT?

Unfortunately not. On the patch #4, I introduce an array to store the
mapping between logical ID and gic ID.
I didn't use this trick here, because the distributor is initialized
before each cpu interface.

>>  So Xen can use the PPI 0 to
>> initialize correctly the routing.
>>
>> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
>> ---
>>  xen/arch/arm/gic.c |    3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
>> index 37a73fb..cadc258 100644
>> --- a/xen/arch/arm/gic.c
>> +++ b/xen/arch/arm/gic.c
>> @@ -275,9 +275,10 @@ void gic_route_dt_irq(const struct dt_irq *irq, const 
>> cpumask_t *cpu_mask,
>>  static void __init gic_dist_init(void)
>>  {
>>      uint32_t type;
>> -    uint32_t cpumask = 1 << smp_processor_id();
>> +    uint32_t cpumask;
>>      int i;
>>  
>> +    cpumask = GICD[GICD_ITARGETSR] & 0xff;
>>      cpumask |= cpumask << 8;
>>      cpumask |= cpumask << 16;
>>  
> 
> 


-- 
Julien Grall

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