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| author | Atish Patra <atish.patra@wdc.com> | 2020-03-17 18:11:44 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-03-31 11:28:30 -0700 |
| commit | f1e58583b9c7ceae7f11646e9edf2561d67f29c9 (patch) | |
| tree | bb55d2b26e3eefea34f6d672cff66b01211d95be /arch/riscv/Kconfig | |
| parent | cfafe260137418d0265d0df3bb18dc494af2b43e (diff) | |
| download | lwn-f1e58583b9c7ceae7f11646e9edf2561d67f29c9.tar.gz lwn-f1e58583b9c7ceae7f11646e9edf2561d67f29c9.zip | |
RISC-V: Support cpu hotplug
This patch enable support for cpu hotplug in RISC-V. It uses SBI HSM
extension to online/offline any hart. As a result, the harts are
returned to firmware once they are offline. If the harts are brought
online afterwards, they re-enter Linux kernel as if a secondary hart
booted for the first time. All booting requirements are honored during
this process.
Tested both on QEMU and HighFive Unleashed board with. Test result follows.
---------------------------------------------------
Offline cpu 2
---------------------------------------------------
$ echo 0 > /sys/devices/system/cpu/cpu2/online
[ 32.828684] CPU2: off
$ cat /proc/cpuinfo
processor : 0
hart : 0
isa : rv64imafdcsu
mmu : sv48
processor : 1
hart : 1
isa : rv64imafdcsu
mmu : sv48
processor : 3
hart : 3
isa : rv64imafdcsu
mmu : sv48
processor : 4
hart : 4
isa : rv64imafdcsu
mmu : sv48
processor : 5
hart : 5
isa : rv64imafdcsu
mmu : sv48
processor : 6
hart : 6
isa : rv64imafdcsu
mmu : sv48
processor : 7
hart : 7
isa : rv64imafdcsu
mmu : sv48
---------------------------------------------------
online cpu 2
---------------------------------------------------
$ echo 1 > /sys/devices/system/cpu/cpu2/online
$ cat /proc/cpuinfo
processor : 0
hart : 0
isa : rv64imafdcsu
mmu : sv48
processor : 1
hart : 1
isa : rv64imafdcsu
mmu : sv48
processor : 2
hart : 2
isa : rv64imafdcsu
mmu : sv48
processor : 3
hart : 3
isa : rv64imafdcsu
mmu : sv48
processor : 4
hart : 4
isa : rv64imafdcsu
mmu : sv48
processor : 5
hart : 5
isa : rv64imafdcsu
mmu : sv48
processor : 6
hart : 6
isa : rv64imafdcsu
mmu : sv48
processor : 7
hart : 7
isa : rv64imafdcsu
mmu : sv48
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'arch/riscv/Kconfig')
| -rw-r--r-- | arch/riscv/Kconfig | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index cac23a5c1104..bc713666f00a 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -20,7 +20,6 @@ config RISCV select CLONE_BACKWARDS select COMMON_CLK select GENERIC_CLOCKEVENTS - select GENERIC_CPU_DEVICES select GENERIC_IRQ_SHOW select GENERIC_PCI_IOMAP select GENERIC_SCHED_CLOCK @@ -254,6 +253,17 @@ config NR_CPUS depends on SMP default "8" +config HOTPLUG_CPU + bool "Support for hot-pluggable CPUs" + depends on SMP + select GENERIC_IRQ_MIGRATION + help + + Say Y here to experiment with turning CPUs off and on. CPUs + can be controlled through /sys/devices/system/cpu. + + Say N if you want to disable CPU hotplug. + choice prompt "CPU Tuning" default TUNE_GENERIC |