[Buildroot] [PATCH 1/8] arch: introduce minimal required gcc version

[Romain Naour <romain.naour@gmail.com>]

Yann, All,

Le 03/09/2017 ? 11:44, Yann E. MORIN a ?crit?:
> Some CPU variants require that a recent-enough gcc be selected. For
> example, ARM's cortex-a35 requires gcc-5, while cortex-a73 requires
> gcc-7. Same goes for other architectures, of course.
> 
> Currently, we hard-code every such conditions in the gcc version choice,
> as well as in the individual external toolchains.
> 
> However, as we add even more CPU variants, the conditions are getting
> more and more complex to write and maintain.
> 
> Introduce new symbols, that architectures can select if they have a
> specific requirement on the gcc version. gcc and external toolchains
> can then properly depend on those symbols.
> 
> The burden of maintaining the requirements on the gcc version now falls
> down to the architeture, instead of being split up in gcc and all the
> external toolchains.
> 
> As the oldest gcc version to handle, we can either choose gcc-4.9, as
> the odlest version we support in our internal toolchain, or choose
> gcc-4.8, as the oldest external toolchain we support (except for the
> custom ones, but they'll be handled specifically in upcoming changes).
> We choose to go back up to gcc-4.8.
> 
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  arch/Config.in | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/arch/Config.in b/arch/Config.in
> index c10bf16809..607da36c1d 100644
> --- a/arch/Config.in
> +++ b/arch/Config.in
> @@ -261,6 +261,27 @@ config BR2_ARCH_HAS_TOOLCHAIN_BUILDROOT
>  	bool
>  	default y if !BR2_ARCH_HAS_NO_TOOLCHAIN_BUILDROOT
>  
> +# The following symbols are selected by the individual
> +# Config.in.$ARCH files

I believe something is missing from this patch.

Best regards,
Romain

> +config BR2_ARCH_NEEDS_GCC_AT_LEAST_4_8
> +	bool
> +
> +config BR2_ARCH_NEEDS_GCC_AT_LEAST_4_9
> +	bool
> +	select BR2_ARCH_NEEDS_GCC_AT_LEAST_4_8
> +
> +config BR2_ARCH_NEEDS_GCC_AT_LEAST_5
> +	bool
> +	select BR2_ARCH_NEEDS_GCC_AT_LEAST_4_9
> +
> +config BR2_ARCH_NEEDS_GCC_AT_LEAST_6
> +	bool
> +	select BR2_ARCH_NEEDS_GCC_AT_LEAST_5
> +
> +config BR2_ARCH_NEEDS_GCC_AT_LEAST_7
> +	bool
> +	select BR2_ARCH_NEEDS_GCC_AT_LEAST_6
> +
>  # The following string values are defined by the individual
>  # Config.in.$ARCH files
>  config BR2_ARCH
>