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| author | Thomas Gleixner <tglx@linutronix.de> | 2023-05-12 23:07:04 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-05-15 13:44:49 +0200 |
| commit | e59e74dc48a309cb848ffc3d76a0d61aa6803c05 (patch) | |
| tree | 9e58c48aff3090ed62f0d81d0f7443160ba82ed7 /Documentation/core-api | |
| parent | x86/smpboot: Rename start_cpu0() to soft_restart_cpu() (diff) | |
| download | linux-e59e74dc48a309cb848ffc3d76a0d61aa6803c05.tar.xz linux-e59e74dc48a309cb848ffc3d76a0d61aa6803c05.zip | |
x86/topology: Remove CPU0 hotplug option
This was introduced together with commit e1c467e69040 ("x86, hotplug: Wake
up CPU0 via NMI instead of INIT, SIPI, SIPI") to eventually support
physical hotplug of CPU0:
"We'll change this code in the future to wake up hard offlined CPU0 if
real platform and request are available."
11 years later this has not happened and physical hotplug is not officially
supported. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.715707999@linutronix.de
Diffstat (limited to 'Documentation/core-api')
| -rw-r--r-- | Documentation/core-api/cpu_hotplug.rst | 13 |
1 files changed, 2 insertions, 11 deletions
diff --git a/Documentation/core-api/cpu_hotplug.rst b/Documentation/core-api/cpu_hotplug.rst index f75778d37488..e6f5bc39cf5c 100644 --- a/Documentation/core-api/cpu_hotplug.rst +++ b/Documentation/core-api/cpu_hotplug.rst @@ -127,17 +127,8 @@ bring CPU4 back online:: $ echo 1 > /sys/devices/system/cpu/cpu4/online smpboot: Booting Node 0 Processor 4 APIC 0x1 -The CPU is usable again. This should work on all CPUs. CPU0 is often special -and excluded from CPU hotplug. On X86 the kernel option -*CONFIG_BOOTPARAM_HOTPLUG_CPU0* has to be enabled in order to be able to -shutdown CPU0. Alternatively the kernel command option *cpu0_hotplug* can be -used. Some known dependencies of CPU0: - -* Resume from hibernate/suspend. Hibernate/suspend will fail if CPU0 is offline. -* PIC interrupts. CPU0 can't be removed if a PIC interrupt is detected. - -Please let Fenghua Yu <fenghua.yu@intel.com> know if you find any dependencies -on CPU0. +The CPU is usable again. This should work on all CPUs, but CPU0 is often special +and excluded from CPU hotplug. The CPU hotplug coordination ============================ |