From: Ashok Raj Date: Sat, 25 Mar 2006 11:06:50 +0000 (-0800) Subject: [PATCH] x86: make CONFIG_HOTPLUG_CPU depend on !X86_PC X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d3f4aaa3d7b4152dac28751ee902f769d03289a1;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git [PATCH] x86: make CONFIG_HOTPLUG_CPU depend on !X86_PC Make 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 when CONFIG_HOTPLUG_CPU=y 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index bfea1bedcbf2..b008fb0cd7b7 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -737,7 +737,7 @@ 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.