Messages in this thread | | | Date | Thu, 05 Dec 2013 21:34:00 +0800 | From | Hanjun Guo <> | Subject | Re: [RFC part2 PATCH 2/9] ARM64 / ACPI: Prefill cpu possible/present maps and map logical cpu id to APIC id |
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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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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