| Message ID | 1345769771-27019-3-git-send-email-fenghua.yu@intel.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Thu, Aug 23, 2012 at 05:56:01PM -0700, Fenghua Yu wrote: > From: Fenghua Yu <fenghua.yu@intel.com> > > New config switch CONFIG_BOOTPARAM_HOTPLUG_CPU0 sets default state of whether > the CPU0 hotplug is on or off. > > If the switch is off, CPU0 is not hotpluggable by default. But the CPU0 hotplug > feature can still be turned on by kernel parameter cpu0_hotplug at boot. > > If the switch is on, CPU0 is always hotpluggable. The default value of > the switch is off. > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> > --- > arch/x86/Kconfig | 29 +++++++++++++++++++++++++++++ > 1 files changed, 29 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 1d91dac..31c8b89 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1711,6 +1711,35 @@ config HOTPLUG_CPU > automatically on SMP systems. ) > Say N if you want to disable CPU hotplug. > > +config BOOTPARAM_HOTPLUG_CPU0 > + bool "Set default setting of cpu0_hotpluggable" Why not change this boot option into something more understandable like bool "BSP hotpluggable by default" or similar? And, btw, maybe I didn't catch this earlier, but why is in all user-visible options the thing called "cpu0_*"? Wouldn't it be better to call it "bsp_*"? Thanks.
> And, btw, maybe I didn't catch this earlier, but why is in all > user-visible options the thing called "cpu0_*"? Wouldn't it be better > to > call it "bsp_*"? The kernel parameter was called bsp_hotplug before. It was changed to cpu0_hotplug in v5 to keep uniform cpu0/CPU0 names. Thanks. -Fenghua
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 1d91dac..31c8b89 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1711,6 +1711,35 @@ config HOTPLUG_CPU automatically on SMP systems. ) Say N if you want to disable CPU hotplug. +config BOOTPARAM_HOTPLUG_CPU0 + bool "Set default setting of cpu0_hotpluggable" + default n + depends on HOTPLUG_CPU && EXPERIMENTAL + ---help--- + Set whether default state of cpu0_hotpluggable is on or off. + + Say Y here to enable CPU0 hotplug by default. If this switch + is turned on, there is no need to give cpu0_hotplug kernel + parameter and the CPU0 hotplug feature is enabled by default. + + Please note: there are two known CPU0 dependencies if you want + to enable the CPU0 hotplug feature either by this switch or by + cpu0_hotplug kernel parameter. + + First, resume from hibernate or suspend always starts from CPU0. + So hibernate and suspend are prevented if CPU0 is offline. + + Second dependency is PIC interrupts always go to CPU0. CPU0 can not + offline if any interrupt can not migrate out of CPU0. There may + be other CPU0 dependencies. + + Please make sure the dependencies are under your control before + you enable this feature. + + Say N if you don't want to enable CPU0 hotplug feature by default. + You still can enable the CPU0 hotplug feature at boot by kernel + parameter cpu0_hotplug. + config COMPAT_VDSO def_bool y prompt "Compat VDSO support"