Messages in this thread | | | Date | Mon, 13 Mar 2006 14:22:23 -0800 | From | Andrew Morton <> | Subject | Re: More than 8 CPUs detected and CONFIG_X86_PC cannot handle it on 2.6.16-rc6 |
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Ashok Raj <ashok.raj@intel.com> wrote: > > > > When CONFIG_HOTPLUG_CPU is turned on we always use physflat mode (bigsmp) even > when #of CPUs are less than 8 to avoid sending IPI to offline processors. > > Without having BIGSMP on it spits out a warning during boot on systems that > seems misleading, since it complains even on systems that have less > than 8 cpus. > > Signed-off-by: Ashok Raj <ashok.raj@intel.com> > --------------------------------------------------------- > > arch/i386/Kconfig | 2 +- > 1 files changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6.16-rc6-mm1/arch/i386/Kconfig > =================================================================== > --- linux-2.6.16-rc6-mm1.orig/arch/i386/Kconfig > +++ linux-2.6.16-rc6-mm1/arch/i386/Kconfig > @@ -760,7 +760,7 @@ config PHYSICAL_START > > config HOTPLUG_CPU > bool "Support for hot-pluggable CPUs (EXPERIMENTAL)" > - depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER > + depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER && !X86_PC > ---help--- > Say Y here to experiment with turning CPUs off and on. CPUs > can be controlled through /sys/devices/system/cpu.
Still seems wrong. People _do_ use HOTPLUG_CPU on X86_PCs so they can get software suspend. The number of people who do this are probably 100000x the number of people who have physically hotpluggable CPUs. And I don't think we can churn their config requirements this much so late in the game.
So for now I suggest we're best off simply killing the printk (or doing something smarter, like comparing cpu_online-map with cpu_possible_map (which isn't right)).
Longer term, it appears that we need to do some Kconfig and C work to separate out the HOTPLUG_CPU infrastructure which swsusp needs from actual CPU hotplugging.
What _is_ this IPI problem anyway? Can't send point-to-point IPIs to offlined CPUs? (Don't do that then?) Or do broadcast IPIs go wrong, or what?
And does it affect pretend-x86-hotplug, or is it only affecting real hotplug?
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