Re: [Buildroot] [PATCH 3/9] arch/powerpc: Enable powerpc64le only on CPUs that support it

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

Joel, All,

On 2022-07-29 09:38 +0930, Joel Stanley spake thusly:
> Invalid configurations lead to build failures, such as trying to enable
> ppc64le for the ppc970:
> 
>   http://autobuild.buildroot.net/results/fda886768fce25ccd9b52b635ff5b13da7ba2d0c/
> 
> In order to run a ppc64le userspace a kernel that runs in this mode is
> required. The only CPU supported in buildroot that can boot a ppc64le
> kernel is Power8, so mark all of the other 64-bit capable CPUs as not
> supporting ppc64le.

Ah, this is where you hide incomatible CPUs for ppc64le. Good. This
should go before your generic CPU patch (patch 2).

Regards,
Yann E. MORIN.

> This drops the comment about libc, which is true but doesn't tell the
> whole story.
> 
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> ---
>  arch/Config.in.powerpc | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/Config.in.powerpc b/arch/Config.in.powerpc
> index 8d392bfde814..7c6ae84348e9 100644
> --- a/arch/Config.in.powerpc
> +++ b/arch/Config.in.powerpc
> @@ -71,11 +71,9 @@ config BR2_powerpc_604e
>  	depends on !BR2_ARCH_IS_64
>  config BR2_powerpc_620
>  	bool "620"
> -	# No C library supports this variant on ppc64le
>  	depends on !BR2_powerpc64le
>  config BR2_powerpc_630
>  	bool "630"
> -	# No C library supports this variant on ppc64le
>  	depends on !BR2_powerpc64le
>  config BR2_powerpc_740
>  	bool "740"
> @@ -102,6 +100,7 @@ config BR2_powerpc_860
>  	depends on !BR2_ARCH_IS_64
>  config BR2_powerpc_970
>  	bool "970"
> +	depends on !BR2_powerpc64le
>  	select BR2_POWERPC_CPU_HAS_ALTIVEC
>  config BR2_powerpc_8540
>  	bool "8540 / e500v1"
> @@ -129,21 +128,25 @@ config BR2_powerpc_e6500
>  	select BR2_POWERPC_CPU_HAS_ALTIVEC
>  config BR2_powerpc_power4
>  	bool "power4"
> -	# No C library supports this variant on ppc64le
>  	depends on !BR2_powerpc64le
>  config BR2_powerpc_power5
>  	bool "power5"
> -	# No C library supports this variant on ppc64le
>  	depends on !BR2_powerpc64le
> +	depends on BR2_ARCH_IS_64

This one is not strictly aout ppc64le. I.e. power5 is not an 32-bit CPU
at all.

Not: I am fine if the change is done in a single patch, but then the
commit should probably be a bit more generic, like

    arch/powerpc: fix variants dependencies

    Only allow variants in the case they are really workable:

      * the only variant in Buildroot that can be a ppc64le is power8

      * 970, power5, power6, and power7, pwer8 are 64-bit only

>  config BR2_powerpc_power6
>  	bool "power6"
> +	depends on !BR2_powerpc64le
> +	depends on BR2_ARCH_IS_64

Ditto, and for the rest too.

>  	select BR2_POWERPC_CPU_HAS_ALTIVEC
>  config BR2_powerpc_power7
>  	bool "power7"
> +	depends on !BR2_powerpc64le
> +	depends on BR2_ARCH_IS_64
>  	select BR2_POWERPC_CPU_HAS_ALTIVEC
>  	select BR2_POWERPC_CPU_HAS_VSX
>  config BR2_powerpc_power8
>  	bool "power8"
> +	depends on BR2_ARCH_IS_64
>  	select BR2_POWERPC_CPU_HAS_ALTIVEC
>  	select BR2_POWERPC_CPU_HAS_VSX
>  endchoice
> -- 
> 2.35.1
> 
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