Hi Stephen, On 15/09/17 02:19, Stephen Boyd wrote: > From what I can see there isn't anything about ACPI_APEI_SEA that > means the arm64 architecture can or cannot support NMI safe > cmpxchg, so the if condition here is not important.
Yup, it was to match 'HAVE_NMI', which was new with ACPI_APEI_SEA and pulls in some printk() stuff. ... how come you don't need to change HAVE_NMI too? > Let's remove > it. Doing that allows us to support ftrace histograms via > CONFIG_HIST_TRIGGERS that depends on the arch having this config > selected. What does CONFIG_HIST_TRIGGERS need this for? I can't see any cmpxchg use in kernel/trace/trace_events_hist.c Regardless, Acked-by: James Morse <james.mo...@arm.com> Thanks, James > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 0df64a6a56d4..27ce2ab7b080 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -21,7 +21,7 @@ config ARM64 > select ARCH_HAS_STRICT_KERNEL_RWX > select ARCH_HAS_STRICT_MODULE_RWX > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > - select ARCH_HAVE_NMI_SAFE_CMPXCHG if ACPI_APEI_SEA > + select ARCH_HAVE_NMI_SAFE_CMPXCHG > select ARCH_USE_CMPXCHG_LOCKREF > select ARCH_SUPPORTS_MEMORY_FAILURE > select ARCH_SUPPORTS_ATOMIC_RMW >