A quick poll of the ARM platforms that implement CPU Hotplug support
shows that every platform treats CPU 0 as a special case that cannot be
hotplugged. In fact every platform has identical code for
platform_cpu_die which returns -EPERM in the case of CPU 0.
The user-facing sysfs interfaces should reflect this by not populating
an 'online' entry for CPU 0 at all. This better reflects reality by
making it clear to users that CPU 0 cannot be hotplugged.
This patch prevents CPU 0 from being marked as hotpluggable on all ARM
platforms during CPU registration. This in turn prevents the creation
of an 'online' sysfs interface for that CPU.
Signed-off-by: Mike Turquette <mturque...@ti.com>
---
arch/arm/kernel/setup.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 70bca64..5f3f4bb 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -949,7 +949,8 @@ static int __init topology_init(void)
for_each_possible_cpu(cpu) {
struct cpuinfo_arm *cpuinfo = &per_cpu(cpu_data, cpu);
- cpuinfo->cpu.hotpluggable = 1;
+ if (cpu)
+ cpuinfo->cpu.hotpluggable = 1;
register_cpu(&cpuinfo->cpu, cpu);
}
--
1.7.4.1
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