Re: [Linaro-acpi] [RFC part2 PATCH 2/9] ARM64 / ACPI: Prefill cpu possible/present maps and map logical cpu id to APIC id

On 2013年12月04日 23:47, Rob Herring wrote:

On Tue, Dec 3, 2013 at 10:39 AM, Hanjun Guo hanjun.guo@linaro.org wrote:

...

When boot the kernel with MADT, the cpu possible and present maps should be prefilled for cpu topology and acpi based cpu hot-plug.

The logic cpu id maps to APIC id (GIC id) is also implemented, it is needed for acpi processor drivers.

Signed-off-by: Hanjun Guo hanjun.guo@linaro.org

arch/arm64/include/asm/acpi.h | 10 ++-- arch/arm64/kernel/setup.c | 2 + arch/arm64/kernel/smp.c | 2 + drivers/acpi/plat/arm-core.c | 118 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 129 insertions(+), 3 deletions(-)

[snip]

...

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index a0c2ca6..1428024 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -420,7 +420,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus) if (err) continue;

+#ifndef CONFIG_ACPI set_cpu_present(cpu, true); +#endif

Should this be moved to DT cpu topology related code?

I didn't see the code in the mainline, Mark Brown is working on it now?

...

             max_cpus--;
     }

} diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c index 45ff625..8527ecc 100644 --- a/drivers/acpi/plat/arm-core.c +++ b/drivers/acpi/plat/arm-core.c

[snip]

...

@@ -221,6 +284,61 @@ static int __init acpi_parse_madt_gic_distributor_entries(void) return 0; }

+static int setup_possible_cpus __initdata = -1; +static int __init _setup_possible_cpus(char *str) +{

•   get_option(&str, &setup_possible_cpus);
  

•   return 0;
  

+} +early_param("possible_cpus", _setup_possible_cpus);

This does not seem ACPI or ARM specific.

...

+/*

• • cpu_possible_mask should be static, it cannot change as cpu's
• • are onlined, or offlined. The reason is per-cpu data-structures
• • are allocated by some modules at init time, and dont expect to
• • do this dynamically on cpu arrival/departure.
• • cpu_present_mask on the other hand can change dynamically.
• • In case when cpu_hotplug is not compiled, then we resort to current
• • behaviour, which is cpu_possible == cpu_present.
• • • Ashok Raj
• • Three ways to find out the number of additional hotplug CPUs:
• • • If the BIOS specified disabled CPUs in ACPI/mptables use that.
• • • The user can overwrite it with possible_cpus=NUM
• • • Otherwise don't reserve additional CPUs.
• • We do this because additional CPUs waste a lot of memory.
• • -AK
• */

+void __init prefill_possible_map(void) +{

•   int i;
  

•   int possible, disabled_cpus;
  

•   disabled_cpus = total_cpus - available_cpus;
  

•   if (setup_possible_cpus == -1) {
  

•           if (disabled_cpus > 0)
  

•                   setup_possible_cpus = disabled_cpus;
  

•           else
  

•                   setup_possible_cpus = 0;
  

•   }
  

•   possible = available_cpus + setup_possible_cpus;
  

•   pr_info("SMP: the system is limited to %d CPUs\n", nr_cpu_ids);
  

•   if (possible > nr_cpu_ids)
  

•           possible = nr_cpu_ids;
  

•   pr_info("SMP: Allowing %d CPUs, %d hotplug CPUs\n",
  

•           possible, max((possible - available_cpus), 0));
  

•   for (i = 0; i < possible; i++)
  

•           set_cpu_possible(i, true);
  

•   for (; i < NR_CPUS; i++)
  

•           set_cpu_possible(i, false);
  

+}

This does not seem ACPI or ARM specific either.

I think possible map here is related to ACPI based CPU hot-plug, that's why I introduce the code here, if anything I'm wrong, please correct me.

Thanks Hanjun