linux-kernel - RE: [PATCH 2/2] powerpc/44x: Remove STDBINUTILS kconfig option

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Message-ID: <e19c6d6bf92d4f7399a939c7c3c7ad0d@AcuMS.aculab.com>
Date:   Wed, 20 Jan 2021 09:33:00 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christophe Leroy' <christophe.leroy@...roup.eu>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "Michael Ellerman" <mpe@...erman.id.au>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/2] powerpc/44x: Remove STDBINUTILS kconfig option

From: Christophe Leroy
> Sent: 20 January 2021 07:49
> 
> STDBINUTILS is just a toggle to allow 256k page size
> to appear in the possible page sizes list for the 44x.
> 
> Make 256k page size appear all the time with an
> explicit warning on binutils, and remove this unneccessary
> STDBINUTILS config option.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>  arch/powerpc/Kconfig | 27 +++++++--------------------
>  1 file changed, 7 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index a685e42d3993..3e29995540a7 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -720,18 +720,6 @@ config ARCH_MEMORY_PROBE
>  	def_bool y
>  	depends on MEMORY_HOTPLUG
> 
> -config STDBINUTILS
> -	bool "Using standard binutils settings"
> -	depends on 44x
> -	default y
> -	help
> -	  Turning this option off allows you to select 256KB PAGE_SIZE on 44x.
> -	  Note, that kernel will be able to run only those applications,
> -	  which had been compiled using binutils later than 2.17.50.0.3 with
> -	  '-zmax-page-size' set to 256K (the default is 64K). Or, if using
> -	  the older binutils, you can patch them with a trivial patch, which
> -	  changes the ELF_MAXPAGESIZE definition from 0x10000 to 0x40000.
> -
>  choice
>  	prompt "Page size"
>  	default PPC_4K_PAGES
> @@ -771,17 +759,16 @@ config PPC_64K_PAGES
>  	select HAVE_ARCH_SOFT_DIRTY if PPC_BOOK3S_64
> 
>  config PPC_256K_PAGES
> -	bool "256k page size"
> -	depends on 44x && !STDBINUTILS && !PPC_47x
> +	bool "256k page size (Requires non-standard binutils settings)"
> +	depends on 44x && !PPC_47x
>  	help
>  	  Make the page size 256k.
> 
> -	  As the ELF standard only requires alignment to support page
> -	  sizes up to 64k, you will need to compile all of your user
> -	  space applications with a non-standard binutils settings
> -	  (see the STDBINUTILS description for details).
> -
> -	  Say N unless you know what you are doing.
> +	  That kernel will be able to run only those applications,
> +	  which had been compiled using binutils later than 2.17.50.0.3 with
> +	  '-zmax-page-size' set to 256K (the default is 64K). Or, if using
> +	  the older binutils, you can patch them with a trivial patch, which
> +	  changes the ELF_MAXPAGESIZE definition from 0x10000 to 0x40000.


The kernel will only be able to run applications that have been
compiled with '-zmax-page-size' set to 256K (the default is 64K)
using binutils later than 2.17.50.0.3, or by patching the
ELF_MAXPAGESIZE definition from 0x10000 to 0x40000 in older versions.

> 
>  endchoice
> 
> --
> 2.25.0

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