path: root/kernel/cpu.c
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authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 19:56:33 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 19:56:33 -0800
commit74b84233458e9db7c160cec67638efdbec748ca9 (patch)
tree0d174c7386386dca17f494396d7febc300ffa3dd /kernel/cpu.c
parent507447473756e316f3f182324071389a51736a83 (diff)
parenta71c8bc5dfefbbf80ef90739791554ef7ea4401b (diff)
Merge branch 'x86-bsp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 BSP hotplug changes from Ingo Molnar: "This tree enables CPU#0 (the boot processor) to be onlined/offlined on x86, just like any other CPU. Enabled on Intel CPUs for now. Allowing this required the identification and fixing of latent CPU#0 assumptions (such as CPU#0 initializations, etc.) in the x86 architecture code, plus the identification of barriers to BSP-offlining, such as active PIC interrupts which can only be serviced on the BSP. It's behind a default-off option, and there's a debug option that allows the automatic testing of this feature. The motivation of this feature is to allow and prepare for true CPU-hotplug hardware support: recent changes to MCE support enable us to detect a deteriorating but not yet hard-failing L1/L2 cache on a CPU that could be soft-unplugged - or a failing L3 cache on a multi-socket system. Note that true hardware hot-plug is not yet fully enabled by this, because that requires a special platform wakeup sequence to be sent to the freshly powered up CPU#0. Future patches for this are planned, once such a platform exists. Chicken and egg" * 'x86-bsp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, topology: Debug CPU0 hotplug x86/i387.c: Initialize thread xstate only on CPU0 only once x86, hotplug: Handle retrigger irq by the first available CPU x86, hotplug: The first online processor saves the MTRR state x86, hotplug: During CPU0 online, enable x2apic, set_numa_node. x86, hotplug: Wake up CPU0 via NMI instead of INIT, SIPI, SIPI x86-32, hotplug: Add start_cpu0() entry point to head_32.S x86-64, hotplug: Add start_cpu0() entry point to head_64.S kernel/cpu.c: Add comment for priority in cpu_hotplug_pm_callback x86, hotplug, suspend: Online CPU0 for suspend or hibernate x86, hotplug: Support functions for CPU0 online/offline x86, topology: Don't offline CPU0 if any PIC irq can not be migrated out of it x86, Kconfig: Add config switch for CPU0 hotplug doc: Add x86 CPU0 online/offline feature
Diffstat (limited to 'kernel/cpu.c')
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index f45657f1eb8e..3046a503242c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -603,6 +603,11 @@ cpu_hotplug_pm_callback(struct notifier_block *nb,
static int __init cpu_hotplug_pm_sync_init(void)
+ /*
+ * cpu_hotplug_pm_callback has higher priority than x86
+ * bsp_pm_callback which depends on cpu_hotplug_pm_callback
+ * to disable cpu hotplug to avoid cpu hotplug race.
+ */
pm_notifier(cpu_hotplug_pm_callback, 0);
return 0;

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