Messages in this thread Patch in this message | | | Date | Wed, 22 Mar 2006 13:00:55 -0800 | From | Ashok Raj <> | Subject | Re: Linux v2.6.16 |
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On Wed, Mar 22, 2006 at 09:40:00PM +0100, Rafael J. Wysocki wrote: > > > > with that patch, try > > > > CONFIG_X86_PC=n > > CONFIG_GENERICARCH=y > > CONFIG_HOTPLUG_CPU=y > > Well, there's nothing like CONFIG_GENERICARCH on x86_64 or I'm obviously > missing something. :-) > > On x86_64 I can choose between X86_PC and X86_VSMP and I'm not sure I'd like > to set X86_VSMP just in order to be able to suspend a box with a dual-core CPU. > IMHO that would be over the top. >
This change is only for i386.. check the patch, its introduced only for arch/i386/Kconfig
There is no change to x86_64, we anyway choose physflat mode in x86_64 which is exactly same as bigsmp in i386.
We didnt change anything in x86_64...Why this speculation :(
Iam attaching that patch for your reference here... in case you lost it and looking at some other patch. :-)
Could you _please_ really check this and tell me if there is real concern... its pretty simple patch... no other arch is affected...
This patch makes CONFIG_HOTPLUG_CPU depend on !X86_PC, so we need to turn on either CONFIG_GENERICARCH, CONFIG_BIGSMP or any other subarch except X86_PC
With 2.6.15+ kernels when CONFIG_HOTPLUG_CPU is turned on we switch to bigsmp mode for sending IPI's and ioapic configurations that caused the following error message.
>> More than 8 CPUs detected and CONFIG_X86_PC cannot handle it. >> Use CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP.
Originally bigsmp was added just to handle >8 cpus, but now with hotplug cpu support we need to use bigsmp mode (why? see below), that cause the above error message even if there were less than 8 cpus in the system.
The message is bogus, but we are cannot use logical flat mode due to issues with broadcast IPI can confuse a CPU just comming up. We use flat physical mode just like x86_64 case. More details on why bigsmp now uses flat physical mode (vs. cluster mode) in following link.
http://marc.theaimsgroup.com/?l=linux-kernel&m=113261865814107&w=2
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. - 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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