Messages in this thread Patch in this message | | | From | "Fenghua Yu" <> | Subject | [PATCH v5 03/12] x86/topology.c: Support functions for CPU0 online/offline | Date | Wed, 11 Jan 2012 09:04:44 -0800 |
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From: Fenghua Yu <fenghua.yu@intel.com>
If CONFIG_BOOTPARAM_HOTPLUG_CPU is turned on, CPU0 hotplug feature is enabled by default.
If CONFIG_BOOTPARAM_HOTPLUG_CPU is not turned on, CPU0 hotplug feature is not enabled by default. The kernel parameter cpu0_hotplug can enable CPU0 hotplug feature at boot.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> --- arch/x86/kernel/topology.c | 27 ++++++++++++++++++++------- 1 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index 76ee977..8cec15c 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -35,18 +35,31 @@ static DEFINE_PER_CPU(struct x86_cpu, cpu_devices); #ifdef CONFIG_HOTPLUG_CPU + +#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0 +static int __initdata cpu0_hotpluggable = 1; +#else +static int __initdata cpu0_hotpluggable; +static int __init enable_cpu0_hotplug(char *str) +{ + cpu0_hotpluggable = 1; + return 1; +} + +__setup("cpu0_hotplug", enable_cpu0_hotplug); +#endif + int __ref arch_register_cpu(int num) { /* - * CPU0 cannot be offlined due to several - * restrictions and assumptions in kernel. This basically - * doesn't add a control file, one cannot attempt to offline - * BSP. + * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate + * depends on BSP. PIC interrupts depend on BSP. * - * Also certain PCI quirks require not to enable hotplug control - * for all CPU's. + * If the BSP depencies are under control, one can tell kernel to + * enable BSP hotplug. This basically adds a control file and + * one can attempt to offline BSP. */ - if (num) + if (num || cpu0_hotpluggable) per_cpu(cpu_devices, num).cpu.hotpluggable = 1; return register_cpu(&per_cpu(cpu_devices, num).cpu, num); -- 1.6.0.3
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