Messages in this thread |  | | | Date | Wed, 5 Oct 2011 21:20:54 +0200 (CEST) | | From | Thomas Gleixner <> | | Subject | Re: [PATCH 6/8] x86, topology.c: Enable CPU0 online/offline |
| |
On Wed, 5 Oct 2011, Fenghua Yu wrote:
> From: Fenghua Yu <fenghua.yu@intel.com> > > Enable CPU0 online/offline by setting up its sysfs control file. By default, > this feature is disabled. You can enabled it by bsp_hotplug kernel option. > > Resume from hibernate, standby, or suspend needs CPU0 online. According to > arch/x86/kernel/topology.c, some PCI quirks(??) need CPU0 online as well. Anyone > knows which PCI quirks depends on CPU0 online? > > Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> > --- > Documentation/kernel-parameters.txt | 7 +++++++ > arch/x86/kernel/topology.c | 22 +++++++++++++++------- > 2 files changed, 22 insertions(+), 7 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 854ed5c..bf011ee 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -1805,6 +1805,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > > nox2apic [X86-64,APIC] Do not enable x2APIC mode. > > + bsp_hotplug [X86] BSP (aka CPU0) is hotpluggable. > + Suspend/resume depends on BSP. It's said some PCI > + quirks depend on BSP too. But not sure which quirks.
Right, not sure what breaks. Go ahead and watch your machine explode.
> + If don't care the dependencies, you can turn on > + bsp_ hotplug. Suspend will fail if BSP is offlined and > + you need to online BSP before suspend/resume.
And you forgot poweroff and reboot, which have similar dependencies on some machines. That whole low level ACPI stuff is sensitive.
> + > nptcg= [IA-64] Override max number of concurrent global TLB > purges which is reported from either PAL_VM_SUMMARY or > SAL PALO. > diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c > index 8927486..ed2da5c 100644 > --- a/arch/x86/kernel/topology.c > +++ b/arch/x86/kernel/topology.c > @@ -34,18 +34,26 @@ > static DEFINE_PER_CPU(struct x86_cpu, cpu_devices); > > #ifdef CONFIG_HOTPLUG_CPU > + > +static int __init enable_bsp_hotplug(char *str) > +{ > + bsp_hotpluggable = 1;
And that variable is defined where? I know where in the following patch, so it's clear that series was neither compiled step per step nor booted.
> + * Suspend/resume depends on BSP. Certain PCI quirks (which PCI > + * quirks??) require not to enable hotplug control for all CPU's.
Again, you dammit better make shure which quirks break when cpu0 is offlined.
Thanks,
tglx
|  |