From 8fea0f59e97df3b9b8d2a76af54f633f4586751b Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Wed, 19 Dec 2018 16:16:47 +0100 Subject: [PATCH] x86/topology: Make DEBUG_HOTPLUG_CPU0 pr_info() more descriptive DEBUG_HOTPLUG_CPU0 debug feature offlines a CPU as early as possible allowing userspace to boot up without that CPU (so that it is possible to check for unwanted dependencies towards the offlined CPU). After doing so it emits a "CPU %u is now offline" pr_info, which is not enough descriptive of why the CPU was offlined (e.g., one might be running with a config that triggered some problem, not being aware that CONFIG_DEBUG_ HOTPLUG_CPU0 is set). Add a bit more of informative text to the pr_info, so that it is immediately obvious why a CPU has been offlined in early boot stages. Background: Got to scratch my head a bit while debugging a WARNING splat related to the offlining of CPU0. Without being aware yet of this debug option it wasn't immediately obvious why CPU0 was being offlined by the kernel. Signed-off-by: Juri Lelli Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: fenghua.yu@intel.com Link: http://lkml.kernel.org/r/20181219151647.15073-1-juri.lelli@redhat.com [ Merge line-broken line. ] Signed-off-by: Ingo Molnar --- arch/x86/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c index 738bf42b0218..be5bc2e47c71 100644 --- a/arch/x86/kernel/topology.c +++ b/arch/x86/kernel/topology.c @@ -71,7 +71,7 @@ int _debug_hotplug_cpu(int cpu, int action) case 0: ret = cpu_down(cpu); if (!ret) { - pr_info("CPU %u is now offline\n", cpu); + pr_info("DEBUG_HOTPLUG_CPU0: CPU %u is now offline\n", cpu); dev->offline = true; kobject_uevent(&dev->kobj, KOBJ_OFFLINE); } else