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[5/7] arm64: Select ARCH_HAS_CPU_RELAX

Message ID 1691581193-8416-6-git-send-email-mihai.carabas@oracle.com (mailing list archive)
State New, archived
Headers show
Series [1/7] cpuidle-haltpoll: Make boot_option_idle_override check X86 specific | expand

Commit Message

Mihai Carabas Aug. 9, 2023, 11:39 a.m. UTC
From: Joao Martins <joao.m.martins@oracle.com>

cpu_relax() is necessary to allow cpuidle poll-state to be used,
so select it from ARM64 kconfig.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

Comments

Peter Zijlstra Aug. 9, 2023, 1:49 p.m. UTC | #1
On Wed, Aug 09, 2023 at 02:39:39PM +0300, Mihai Carabas wrote:
> From: Joao Martins <joao.m.martins@oracle.com>
> 
> cpu_relax() is necessary to allow cpuidle poll-state to be used,
> so select it from ARM64 kconfig.
> 
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
> ---
>  arch/arm64/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 87ade6549790..7c47617b5722 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -105,6 +105,7 @@ config ARM64
>  	select ARCH_WANT_LD_ORPHAN_WARN
>  	select ARCH_WANTS_NO_INSTR
>  	select ARCH_WANTS_THP_SWAP if ARM64_4K_PAGES
> +	select ARCH_HAS_CPU_RELAX
>  	select ARCH_HAS_UBSAN_SANITIZE_ALL
>  	select ARM_AMBA
>  	select ARM_ARCH_TIMER

Uh what ?! cpu_relax() is assumed present on all archs, no?
Russell King (Oracle) Aug. 29, 2023, 2:49 p.m. UTC | #2
On Wed, Aug 09, 2023 at 03:49:41PM +0200, Peter Zijlstra wrote:
> On Wed, Aug 09, 2023 at 02:39:39PM +0300, Mihai Carabas wrote:
> > From: Joao Martins <joao.m.martins@oracle.com>
> > 
> > cpu_relax() is necessary to allow cpuidle poll-state to be used,
> > so select it from ARM64 kconfig.
> > 
> > Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> > Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
> > ---
> >  arch/arm64/Kconfig | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 87ade6549790..7c47617b5722 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -105,6 +105,7 @@ config ARM64
> >  	select ARCH_WANT_LD_ORPHAN_WARN
> >  	select ARCH_WANTS_NO_INSTR
> >  	select ARCH_WANTS_THP_SWAP if ARM64_4K_PAGES
> > +	select ARCH_HAS_CPU_RELAX
> >  	select ARCH_HAS_UBSAN_SANITIZE_ALL
> >  	select ARM_AMBA
> >  	select ARM_ARCH_TIMER
> 
> Uh what ?! cpu_relax() is assumed present on all archs, no?

I think you have x86 to blame for that!

That symbol is used in drivers/acpi/processor_idle.c to setup stuff
for the cpuidle polling, and also by cpuidle's Makefile to build
poll_state.o

It isn't to do with the presence of cpu_relax() or not.

It probably ought to be renamed to CPUIDLE_CPU_RELAX which would
better describe its modern purpose.
diff mbox series

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 87ade6549790..7c47617b5722 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -105,6 +105,7 @@  config ARM64
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANTS_THP_SWAP if ARM64_4K_PAGES
+	select ARCH_HAS_CPU_RELAX
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARM_AMBA
 	select ARM_ARCH_TIMER