On 2 March 2018 at 17:06, Alistair Francis <alistair.fran...@xilinx.com> wrote:
Subject should say "core count" rather than "cluster size" ?
> The cortex A53 TRM specifices that bits 24 and 25 of the L2CTLR register
"specifies"
> specify the number of cores present and not the number of processors. To
"the number of cores in the processor, not the total number of cores
in the system".
> report this correctly on machines with multiple CPU clusters (ARM's
> big.LITTLE or Xilinx's ZynqMP) we need to allow the machine to overwrite
> this value. To do this let's add an optional property.
>
> Signed-off-by: Alistair Francis <alistair.fran...@xilinx.com>
> ---
>
> target/arm/cpu.h | 5 +++++
> target/arm/cpu.c | 1 +
> target/arm/cpu64.c | 11 +++++++++--
> 3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/target/arm/cpu.h b/target/arm/cpu.h
> index 8dd6b788df..3fa8fdad21 100644
> --- a/target/arm/cpu.h
> +++ b/target/arm/cpu.h
> @@ -745,6 +745,11 @@ struct ARMCPU {
> /* Uniprocessor system with MP extensions */
> bool mp_is_up;
>
> + /* Specify the number of cores in this CPU cluster. Used for the L2CTLR
> + * register.
> + */
> + int32_t core_count;
> +
> /* The instance init functions for implementation-specific subclasses
> * set these fields to specify the implementation-dependent values of
> * various constant registers and reset values of non-constant
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index 6b77aaa445..7a17ba1418 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -1765,6 +1765,7 @@ static Property arm_cpu_properties[] = {
> DEFINE_PROP_UINT64("mp-affinity", ARMCPU,
> mp_affinity, ARM64_AFFINITY_INVALID),
> DEFINE_PROP_INT32("node-id", ARMCPU, node_id, CPU_UNSET_NUMA_NODE_ID),
> + DEFINE_PROP_INT32("core-count", ARMCPU, core_count, -1),
> DEFINE_PROP_END_OF_LIST()
> };
>
> diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
> index 4228713b19..5e5ae44aeb 100644
> --- a/target/arm/cpu64.c
> +++ b/target/arm/cpu64.c
> @@ -42,8 +42,15 @@ static inline void unset_feature(CPUARMState *env, int
> feature)
> #ifndef CONFIG_USER_ONLY
> static uint64_t a57_a53_l2ctlr_read(CPUARMState *env, const ARMCPRegInfo *ri)
> {
> - /* Number of processors is in [25:24]; otherwise we RAZ */
> - return (smp_cpus - 1) << 24;
> + ARMCPU *cpu = arm_env_get_cpu(env);
> +
> + /* Number of cores is in [25:24]; otherwise we RAZ */
> + if (cpu->core_count == -1) {
> + /* No core_count specified, default to smp_cpus. */
> + return (smp_cpus - 1) << 24;
> + } else {
> + return (cpu->core_count - 1) << 24;
> + }
> }
> #endif
I think having arm_cpu_realizefn do
if (cpu->core_count == -1) {
cpu->core_count = smp_cpus;
}
would be neater than doing that check when the register is read.
thanks
-- PMM
