Re: [Buildroot] [PATCH 1/9] arch/powerpc: Hide SPE ABI behind CPU type

From: "Yann E. MORIN" <yann.morin.1998@free.fr>
To: Joel Stanley <joel@jms.id.au>
Cc: "Bernd Kuhls" <bernd.kuhls@t-online.de>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	buildroot@buildroot.org, "Romain Naour" <romain.naour@gmail.com>
Subject: Re: [Buildroot] [PATCH 1/9] arch/powerpc: Hide SPE ABI behind CPU type
Date: Fri, 29 Jul 2022 23:17:55 +0200	[thread overview]
Message-ID: <20220729211755.GE1554632@scaer> (raw)
In-Reply-To: <20220729000904.1295295-2-joel@jms.id.au>

Joel, All,

On 2022-07-29 09:38 +0930, Joel Stanley spake thusly:
> The target ABI option for PowerPC is for selecting the SPE ABI, not the
> ELF ABI that users may expect.
> 
> Hide it when there is no option available to make it clearer when
> browsing menuconfig.
> 
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> ---
>  arch/Config.in.powerpc | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/Config.in.powerpc b/arch/Config.in.powerpc
> index c48edd3bb40c..ef0e85fec680 100644
> --- a/arch/Config.in.powerpc
> +++ b/arch/Config.in.powerpc
> @@ -143,6 +143,7 @@ config BR2_powerpc_power8
>  	select BR2_POWERPC_CPU_HAS_VSX
>  endchoice
>  
> +if BR2_POWERPC_CPU_HAS_SPE
>  choice
>  	prompt "Target ABI"
>  	default BR2_powerpc_SPE if BR2_POWERPC_CPU_HAS_SPE
> @@ -157,6 +158,7 @@ config BR2_powerpc_SPE
>  	bool "SPE"
>  	depends on BR2_POWERPC_CPU_HAS_SPE
>  endchoice
> +endif

I don't understand this change. Currently we have:

 1. If BR2_POWERPC_CPU_HAS_SPE=y:
    BR2_powerpc_CLASSIC is not selectable
    BR2_powerpc_SPE is the only choice

  2. if BR2_POWERPC_CPU_HAS_SPE is not set:
    BR2_powerpc_CLASSIC is the only choice
    BR2_powerpc_SPE is not selectable

This means that the choice was really nt a choice, because the value of
HAS_SPE implies which option is settable or not.

With your change, the BR2_powerpc_CLASSIC will never be selectable at
all, and BR2_powerpc_SPE will be forcibly set when
BR2_POWERPC_CPU_HAS_SPE=y

So we should just drop the choice altogether, and use the SPE ABI when
the CPu has SPE.

Is that what your patch was aiming at?

Regards,
Yann E. MORIN.

>  config BR2_POWERPC_SOFT_FLOAT
>  	bool "Use soft-float"
> -- 
> 2.35.1
> 
> _______________________________________________
> buildroot mailing list
> buildroot@buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot

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