On 2014-7-29 2:51, Sudeep Holla wrote:

On 24/07/14 14:00, Hanjun Guo wrote:

quoted

arch_fix_phys_package_id() will be called in ACPI core to use
the slot number provided by ACPI to update the physical package
id, then we can get the right value in the "physical id" field
of /proc/cpuinfo.

Signed-off-by: Hanjun Guo <redacted>
---
  arch/arm64/include/asm/topology.h |    2 ++
  arch/arm64/kernel/topology.c      |   14 ++++++++++++++
  2 files changed, 16 insertions(+)

diff --git a/arch/arm64/include/asm/topology.h

b/arch/arm64/include/asm/topology.h
index 7ebcd31..2b216d4 100644

--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h

@@ -23,11 +23,13 @@ extern struct cpu_topology cpu_topology[NR_CPUS];
  void init_cpu_topology(void);
  void store_cpu_topology(unsigned int cpuid);
  const struct cpumask *cpu_coregroup_mask(int cpu);
+void arch_fix_phys_package_id(int num, u32 slot);

  #else

  static inline void init_cpu_topology(void) { }
  static inline void store_cpu_topology(unsigned int cpuid) { }
+static inline void arch_fix_phys_package_id(int num, u32 slot) { }

  #endif

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 43514f9..c547885 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c

@@ -281,3 +281,17 @@ void __init init_cpu_topology(void)
      if (parse_dt_topology())
          reset_cpu_topology();
  }
+
+/*
+ * Use the CPU slot number provided by ACPI to update the physical
+ * package id when cpuid_topo->cluster_id is not available, then we
+ * can get the right value in the "physical id" field of /proc/cpuinfo.
+ */

We don't have "physical id" field in /proc/cpuinfo on ARM64.

I'm just curious, if there are two or more CPU (SoC) chips and connected
into one system, how to tell one SoC from another?

quoted

+void arch_fix_phys_package_id(int num, u32 slot)
+{
+    struct cpu_topology *cpuid_topo = &cpu_topology[num];
+
+    if (cpuid_topo->cluster_id == -1)
+        cpuid_topo->cluster_id = slot;
+}
+EXPORT_SYMBOL_GPL(arch_fix_phys_package_id);

The ACPI core uses this function to set the package id as read from
_SUN from the device. As per spec, _SUN is used by OSPM UI to identify
slots for the user. Do we know how will this be used on ARM64 ?

If not clear at this time, better to define it or keep it empty. I see
even x86 does nothing in that function.

I'm ok with it, will introduce a stub function for it and remove this patch.

Thanks
Hanjun