CPU hotplug shall be disabled
Bug #1401018 reported by
Ike Panhc
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux-keystone (Ubuntu) |
Fix Released
|
Medium
|
Ike Panhc |
Bug Description
debian.
We do not support cpu hotplug and it shall be disabled.
Related branches
Changed in linux-keystone (Ubuntu): | |
importance: | Undecided → Medium |
tags: | added: patch |
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By disabling CONFIG_HOTPLUG_CPU for slayton the interfaces 'online' and 'offline' and not exposed in /sys/devices/ system/ cpu/cpuX/ . Therefore we can prevent applications or users trying to offline CPUs.
To enable cpu offline, TI will need to implement this feature in arm/mach- keystone/ by providing appropriate functions for .cpu_disable, .cpu_die and .cpu_kill.
linux/arch/
For example with CONFIG_HOTPLUG_CPU disabled in config we have:
ubuntu@ ubuntu: /sys/devices/ system/ cpu$ tree siblings_ list siblings_ list siblings_ list siblings_ list
.
|-- cpu0
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_
| `-- uevent
|-- cpu1
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_
| `-- uevent
|-- cpu2
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_
| `-- uevent
|-- cpu3
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_
| `-- uevent
|-- cpuidle
| |-- current_driver
| `-- current_governor_ro
|-- kernel_max
|-- offline
|-- online
|-- possible
|-- present
`-- uevent
setting 0 to /sys/devices/ system/ cpu/online would produce a message.
root@ubuntu: /home/ubuntu# echo 0 > /sys/devices/ system/ cpu/online system/ cpu/online: Permission denied /home/ubuntu#
bash: /sys/devices/
root@ubuntu: