Re: [Qemu-devel] [PATCH v2 1/5] target-arm: Add the pmceid0 and pmceid1 registers

[Christopher Covington <cov@codeaurora.org>]

On 02/09/2016 12:19 PM, Peter Maydell wrote:
> On 6 February 2016 at 00:55, Alistair Francis
> <alistair.francis@xilinx.com> wrote:
>> Signed-off-by: Aaron Lindsay <alindsay@codeaurora.org>
>> Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
>> Tested-by: Nathan Rossi <nathan@nathanrossi.com>
>> ---
>>
>>  target-arm/cpu-qom.h | 2 ++
>>  target-arm/cpu.c     | 2 ++
>>  target-arm/cpu64.c   | 2 ++
>>  target-arm/helper.c  | 8 ++++++++
>>  4 files changed, 14 insertions(+)
>>
>> diff --git a/target-arm/cpu-qom.h b/target-arm/cpu-qom.h
>> index 07c0a71..1cc4502 100644
>> --- a/target-arm/cpu-qom.h
>> +++ b/target-arm/cpu-qom.h
>> @@ -148,6 +148,8 @@ typedef struct ARMCPU {
>>      uint32_t id_pfr0;
>>      uint32_t id_pfr1;
>>      uint32_t id_dfr0;
>> +    uint32_t pmceid0;
>> +    uint32_t pmceid1;
>>      uint32_t id_afr0;
>>      uint32_t id_mmfr0;
>>      uint32_t id_mmfr1;
>> diff --git a/target-arm/cpu.c b/target-arm/cpu.c
>> index 7ddbf3d..937f845 100644
>> --- a/target-arm/cpu.c
>> +++ b/target-arm/cpu.c
>> @@ -1156,6 +1156,8 @@ static void cortex_a15_initfn(Object *obj)
>>      cpu->id_pfr0 = 0x00001131;
>>      cpu->id_pfr1 = 0x00011011;
>>      cpu->id_dfr0 = 0x02010555;
>> +    cpu->pmceid0 = 0x00000481; /* PMUv3 events 0x0, 0x8, and 0x11 */
> 
> These are:
>  SW_INCR   # insn architecturally executed, cc pass, software increment
>  INST_RETIRED # insn architecturally executed
>  CPU_CYCLES # cycle
> 
> However we don't actually implement any of these, so should
> we be advertising them?

Perhaps I'm missing something, but I was under the impression that CPU
cycle accounting was implemented as pmccntr_read/write in
target-arm/helper.c.

The instruction count event may need a wrapper around cpu_get_icount().

SWINC is pretty trivial, but I don't think we actually use it, other
than for some testing (but unfortunately not yet part of the
kvm-unit-tests patchset).

Thanks,
Cov

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