Re: [Qemu-devel] [PATCH 2/9] hw/arm_gic: Remove the special casing of NCPU for the NVIC

[Peter Maydell]

On 18 May 2012 14:01, Andreas Färber <address@hidden> wrote:
> Am 02.05.2012 19:12, schrieb Peter Maydell:
>> Drop the special casing of NCPU=1 for the NVIC. This slightly
>> increases the amount of memory used by its state structure,
>> but removes some ifdeffery and means we can safely move the
>> GIC state into a common subclass structure.
>>
>> Signed-off-by: Peter Maydell <address@hidden>
>> ---
>>  hw/arm_gic.c     |   23 +++--------------------
>>  hw/armv7m_nvic.c |    5 ++---
>>  2 files changed, 5 insertions(+), 23 deletions(-)
>>
>> diff --git a/hw/arm_gic.c b/hw/arm_gic.c
>> index 17b2eba..2d8ceb8 100644
>> --- a/hw/arm_gic.c
>> +++ b/hw/arm_gic.c
> [...]
>> @@ -131,11 +123,9 @@ typedef struct gic_state
>>
>>  static inline int gic_get_current_cpu(gic_state *s)
>>  {
>> -#if NCPU > 1
>>      if (s->num_cpu > 1) {
>>          return cpu_single_env->cpu_index;
>>      }
>> -#endif
>>      return 0;
>>  }
>
> Why special-case the num_cpu == 1 case? Is cpu_single_env not available
> in all cases?

The "realview_gic" device uses this GIC as a board-level
(ie not built into the CPU) GIC. In that case there might
be a multicore CPU (with its own GIC) but the boardlevel
GIC is still single-CPU-interface, so gic_get_current_cpu
needs to return 0 whichever CPU core is reading it.

-- PMM