[PATCH v2] arm64: Kconfig: add a choice for endianness

[PATCH v2] arm64: Kconfig: add a choice for endianness

[Anders Roxell]

When building allmodconfig KCONFIG_ALLCONFIG=$(pwd)/arch/arm64/configs/defconfig
CONFIG_CPU_BIG_ENDIAN gets enabled. Which tends not to be what most
people want. Another concern that has come up is that ACPI isn't built
for an allmodconfig kernel today since that also depends on !CPU_BIG_ENDIAN.

Rework so that we introduce a 'choice' and default the choice to
CPU_LITTLE_ENDIAN. That means that when we build an allmodconfig kernel
it will default to CPU_LITTLE_ENDIAN that most people tends to want.

Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 arch/arm64/Kconfig | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 64764ca92fca..c599b6b288be 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -877,10 +877,26 @@ config ARM64_PA_BITS
 	default 48 if ARM64_PA_BITS_48
 	default 52 if ARM64_PA_BITS_52
 
+choice
+	prompt "Endianness"
+	default CPU_LITTLE_ENDIAN
+	help
+	  Select the endianness of data accesses performed by the CPU. Userspace
+	  applications will need to be compiled and linked for the endianness
+	  that is selected here.
+
 config CPU_BIG_ENDIAN
        bool "Build big-endian kernel"
        help
-         Say Y if you plan on running a kernel in big-endian mode.
+	  Say Y if you plan on running a kernel with a big-endian userspace.
+
+config CPU_LITTLE_ENDIAN
+	bool "Build little-endian kernel"
+	help
+	  Say Y if you plan on running a kernel with a little-endian userspace.
+	  This is usually the case for distributions targetting arm64.
+
+endchoice
 
 config SCHED_MC
 	bool "Multi-core scheduler support"
-- 
2.20.1

Re: [PATCH v2] arm64: Kconfig: add a choice for endianness

[Will Deacon]

On Wed, Nov 13, 2019 at 10:26:52AM +0100, Anders Roxell wrote:
> When building allmodconfig KCONFIG_ALLCONFIG=$(pwd)/arch/arm64/configs/defconfig
> CONFIG_CPU_BIG_ENDIAN gets enabled. Which tends not to be what most
> people want. Another concern that has come up is that ACPI isn't built
> for an allmodconfig kernel today since that also depends on !CPU_BIG_ENDIAN.
> 
> Rework so that we introduce a 'choice' and default the choice to
> CPU_LITTLE_ENDIAN. That means that when we build an allmodconfig kernel
> it will default to CPU_LITTLE_ENDIAN that most people tends to want.
> 
> Reviewed-by: John Garry <john.garry@huawei.com>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>  arch/arm64/Kconfig | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 64764ca92fca..c599b6b288be 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -877,10 +877,26 @@ config ARM64_PA_BITS
>  	default 48 if ARM64_PA_BITS_48
>  	default 52 if ARM64_PA_BITS_52
>  
> +choice
> +	prompt "Endianness"
> +	default CPU_LITTLE_ENDIAN
> +	help
> +	  Select the endianness of data accesses performed by the CPU. Userspace
> +	  applications will need to be compiled and linked for the endianness
> +	  that is selected here.
> +
>  config CPU_BIG_ENDIAN
>         bool "Build big-endian kernel"
>         help
> -         Say Y if you plan on running a kernel in big-endian mode.
> +	  Say Y if you plan on running a kernel with a big-endian userspace.
> +
> +config CPU_LITTLE_ENDIAN
> +	bool "Build little-endian kernel"
> +	help
> +	  Say Y if you plan on running a kernel with a little-endian userspace.
> +	  This is usually the case for distributions targetting arm64.

Bah, my typo here: targetting -> targeting

Catalin, could you take this with the above fixed, please?

Acked-by: Will Deacon <will@kernel.org>

Will

Re: [PATCH v2] arm64: Kconfig: add a choice for endianness

[Catalin Marinas]

On Wed, Nov 13, 2019 at 10:26:52AM +0100, Anders Roxell wrote:
> When building allmodconfig KCONFIG_ALLCONFIG=$(pwd)/arch/arm64/configs/defconfig
> CONFIG_CPU_BIG_ENDIAN gets enabled. Which tends not to be what most
> people want. Another concern that has come up is that ACPI isn't built
> for an allmodconfig kernel today since that also depends on !CPU_BIG_ENDIAN.
> 
> Rework so that we introduce a 'choice' and default the choice to
> CPU_LITTLE_ENDIAN. That means that when we build an allmodconfig kernel
> it will default to CPU_LITTLE_ENDIAN that most people tends to want.
> 
> Reviewed-by: John Garry <john.garry@huawei.com>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

Queued for 5.5 (with the typo fixed). Thanks.

-- 
Catalin