[Buildroot] [PATCH] linux: allow the selection of the architecture's default configuration

[Yann E. MORIN <yann.morin.1998@free.fr>]

Thomas, Naresh, All,

On 2016-06-14 12:19 +0200, Thomas Petazzoni spake thusly:
> To configure the Linux kernel, we currently provide two options:
> 
>  1. Passing a defconfig name (for example "multi_v7"), to which we append
>     "_defconfig" to run "make multi_v7_defconfig".
> 
>  2. Passing a path to a custom configuration file.
> 
> Unfortunately, those two possibilities do not allow to configure the
> kernel when you want to use the default configuration built into the
> kernel for a given architecture. For example, on ARM64, there is a
> single defconfig simply called "defconfig", which you can load by
> running "make defconfig".
> 
> Using the mechanism (1) above doesn't work because we append
> "_defconfig" automatically.
> 
> One solution would be to change (1) and require the user to enter the
> full defconfig named (i.e "multi_v7_defconfig" instead of "multi_v7"),
> but we would break all existing Buildroot configurations.
> 
> So instead, we add a third option, which simply tells Buildroot to use
> the default configuration for the selected architecture. In this case,
> Buildroot will configure the kernel by running "make defconfig".
> 
> Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

> ---
> This proposal aims at replacing:
> 
>   https://patchwork.ozlabs.org/patch/616638/
>   https://patchwork.ozlabs.org/patch/612216/
> 
> with a solution that 1/ doesn't break existing Buildroot
> configuration (which proposal 616638 was doing), and 2/ works fine even
> if the architecture also provides non-default defconfigs (which was an
> issue with proposal 612216).
> 
> I've marked both of these patches as Superdeded in patchwork.
> ---
>  linux/Config.in | 8 ++++++++
>  linux/linux.mk  | 2 ++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/linux/Config.in b/linux/Config.in
> index ce55271..be6d0cc 100644
> --- a/linux/Config.in
> +++ b/linux/Config.in
> @@ -142,6 +142,14 @@ choice
>  config BR2_LINUX_KERNEL_USE_DEFCONFIG
>  	bool "Using an in-tree defconfig file"
>  
> +config BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG
> +	bool "Use the architecture default configuration"
> +	help
> +	  This option will use the default configuration for the
> +	  selected architecture. I.e, it is equivalent to running
> +	  "make ARCH=<foo> defconfig". This is useful on architectures
> +	  that have a single defconfig file, such as ARM64.
> +
>  config BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG
>  	bool "Using a custom (def)config file"
>  
> diff --git a/linux/linux.mk b/linux/linux.mk
> index a751da9..fb844ef 100644
> --- a/linux/linux.mk
> +++ b/linux/linux.mk
> @@ -206,6 +206,8 @@ LINUX_POST_PATCH_HOOKS += LINUX_TRY_PATCH_TIMECONST
>  
>  ifeq ($(BR2_LINUX_KERNEL_USE_DEFCONFIG),y)
>  LINUX_KCONFIG_DEFCONFIG = $(call qstrip,$(BR2_LINUX_KERNEL_DEFCONFIG))_defconfig
> +else ifeq ($(BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG),y)
> +LINUX_KCONFIG_DEFCONFIG = defconfig
>  else ifeq ($(BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG),y)
>  LINUX_KCONFIG_FILE = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE))
>  endif
> -- 
> 2.7.4
> 
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> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

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