CPU hotplug shall be disabled

Bug #1401018 reported by Ike Panhc on 2014-12-10
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux-keystone (Ubuntu)
Medium
Ike Panhc

Bug Description

debian.keystone/config/config.common.ubuntu:CONFIG_HOTPLUG_CPU=y

We do not support cpu hotplug and it shall be disabled.

Ike Panhc (ikepanhc) on 2014-12-10
Changed in linux-keystone (Ubuntu):
importance: Undecided → Medium
Manoj Iyer (manjo) wrote :

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
linux/arch/arm/mach-keystone/ by providing appropriate functions for .cpu_disable, .cpu_die and .cpu_kill.

For example with CONFIG_HOTPLUG_CPU disabled in config we have:

ubuntu@ubuntu:/sys/devices/system/cpu$ tree
.
|-- cpu0
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_siblings_list
| `-- uevent
|-- cpu1
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_siblings_list
| `-- uevent
|-- cpu2
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_siblings_list
| `-- uevent
|-- cpu3
| |-- subsystem -> ../../../../bus/cpu
| |-- topology
| | |-- core_id
| | |-- core_siblings
| | |-- core_siblings_list
| | |-- physical_package_id
| | |-- thread_siblings
| | `-- thread_siblings_list
| `-- 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
bash: /sys/devices/system/cpu/online: Permission denied
root@ubuntu:/home/ubuntu#

Ike Panhc (ikepanhc) wrote :

In order to disable HOTPLUG_CPU, either SMP or SUSPEND shall be disabled. I do not think keystone platform support for suspend so CONFIG_SUSPEND shall be disabled also.

Changed in linux-keystone (Ubuntu):
status: Confirmed → In Progress
tags: added: patch
Launchpad Janitor (janitor) wrote :
Download full text (10.9 KiB)

This bug was fixed in the package linux-keystone - 3.13.0-20.33

---------------
linux-keystone (3.13.0-20.33) trusty; urgency=low

  [ Ike Panhc ]

  * Release Tracking Bug
    - LP: #1402951
  * [Config] Disable SUSPEND and HOTPLUG_CPU
    - LP: #1401018
  * Rebase to Ubuntu-3.13.0-44.73

  [ Ubuntu: 3.13.0-44.73 ]

  * Release Tracking Bug
    - LP: #1402872
  * SAUCE: Add use_native_backlight quirk for HP ProBook 6570b
    - LP: #1359010
  * Revert "SAUCE: (no-up) arm64: optimized copy_to_user and copy_from_user
    assembly code"
    - LP: #1398596
  * [Config] updateconfigs to balance CONFIG_SCOM_DEBUGFS
  * iwlwifi: mvm: fix merge damage
    - LP: #1393317
  * iwlwifi: remove IWL_UCODE_TLV_FLAGS_SCHED_SCAN flag
    - LP: #1393317
  * iwlwifi: mvm: disable scheduled scan to prevent firmware crash
    - LP: #1393317
  * iwlwifi: mvm: enable scheduled scan on newest firmware
    - LP: #1393317
  * x86: kvm: use alternatives for VMCALL vs. VMMCALL if kernel text is
    read-only
    - LP: #1379340
  * phylib: introduce PHY_INTERFACE_MODE_XGMII for 10G PHY
    - LP: #1381084
  * of: make of_get_phy_mode parse 'phy-connection-type'
    - LP: #1381084
  * xen-netfront: Remove BUGs on paged skb data which crosses a page
    boundary
    - LP: #1275879
  * ACPI / blacklist: blacklist Win8 OSI for Dell Vostro 3546
    - LP: #1383589
  * powerpc/pseries: Fix endiannes issue in RTAS call from xmon
    - LP: #1396235
  * mmc: sdhci-pci-o2micro: Fix Dell E5440 issue
    - LP: #1346067
  * mfd: rtsx: Fix PM suspend for 5227 & 5249
    - LP: #1359052
  * drivers:scsi:storvsc: Fix a bug in handling ring buffer failures that
    may result in I/O freeze
    - LP: #1400289
  * arm64: optimized copy_to_user and copy_from_user assembly code
    - LP: #1400349
  * net:socket: set msg_namelen to 0 if msg_name is passed as NULL in
    msghdr struct from userland.
    - LP: #1335478
  * drm/radeon: initialize sadb to NULL in the audio code
    - LP: #1402714
  * powerpc/vphn: NUMA node code expects big-endian
    - LP: #1401150
  * ALSA: usb-audio: Fix device_del() sysfs warnings at disconnect
    - LP: #1402853
  * ALSA: hda - Add mute LED pin quirk for HP 15 touchsmart
    - LP: #1334950, #1402853
  * rcu: Make callers awaken grace-period kthread
    - LP: #1402853
  * rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads
    - LP: #1402853
  * net: sctp: fix NULL pointer dereference in af->from_addr_param on
    malformed packet
    - LP: #1402853
  * KVM: x86: Don't report guest userspace emulation error to userspace
    - LP: #1402853
  * [media] ttusb-dec: buffer overflow in ioctl
    - LP: #1402853
  * arm64: __clear_user: handle exceptions on strb
    - LP: #1402853
  * ARM: pxa: fix hang on startup with DEBUG_LL
    - LP: #1402853
  * samsung-laptop: Add broken-acpi-video quirk for NC210/NC110
    - LP: #1402853
  * acer-wmi: Add Aspire 5741 to video_vendor_dmi_table
    - LP: #1402853
  * acer-wmi: Add acpi_backlight=video quirk for the Acer KAV80
    - LP: #1402853
  * rbd: Fix error recovery in rbd_obj_read_sync()
    - LP: #1402853
  * [media] ds3000: fix LNB supply voltage on Tevii S480 on initialization
    - LP: #1402853
  * powerpc: ...

Changed in linux-keystone (Ubuntu):
status: In Progress → Fix Released
status: In Progress → Fix Released
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