Re: [PATCH v2 02/19] ARM: limit OABI support to StrongARM CPUs

[Alexandre Belloni <alexandre.belloni@bootlin.com>]

On 01/07/2026 23:23:36+0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> As discussed on the mailing lists, there is no way to build OABI userspace
> binaries any more since gcc-4.8, and now support is also getting dropped in
> binutils, which will make it impossible to build pure OABI kernels at some
> point in the future.
> 
> I found no evidence of anyone still sing OABI userspace on embedded systems
> that keep getting kernel updates, but there are a few desktop-class machines
> that date back to the 1990s using Intel StrongARM processors that were
> supported by old versions of Debian, Red Hat or the official Corel
> Netwinder distribution.
> 
> Add a much stricter Kconfig dependency for both native OABI and OABI_COMPAT
> enabled kernels, only allowing either of them to be selected when building
> a kernel that targets a StrongARM based machine.
> 
> Link: https://lore.kernel.org/lkml/2831c5a6-cfbf-4fe0-b51c-0396e5b0aeb7@app.fastmail.com/
> Acked-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/arm/Kconfig                       | 14 +++++++-------
>  arch/arm/configs/am200epdkit_defconfig |  1 -
>  arch/arm/configs/axm55xx_defconfig     |  1 -
>  arch/arm/configs/footbridge_defconfig  |  2 +-
>  arch/arm/configs/neponset_defconfig    |  2 +-
>  arch/arm/configs/versatile_defconfig   |  1 -
>  6 files changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index ccc0114d30de..3b2316dc9d13 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1151,8 +1151,7 @@ config ARM_PATCH_IDIV
>  	  code to do integer division.
>  
>  config AEABI
> -	bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \
> -		!CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG
> +	bool "Use the ARM EABI to compile the kernel" if CPU_SA110 || CPU_SA1100
>  	default y
>  	help
>  	  The Arm EABI is the default ABI on all modern Linux
> @@ -1162,9 +1161,13 @@ config AEABI
>  	  Everyone should enable this, as support for OABI user space
>  	  was dropped in gcc-4.8 and most distributions after ca. 2013.
>  
> +	  Support for OABI mode will be removed from the kernel
> +	  once Intel StrongARM CPUs are phased out.
> +
>  config OABI_COMPAT
>  	bool "Allow old ABI binaries to run with this kernel (EXPERIMENTAL)"
>  	depends on AEABI && !THUMB2_KERNEL
> +	depends on CPU_SA110 || CPU_SA1100
>  	help
>  	  This option preserves the old syscall interface along with the
>  	  new (ARM EABI) one. It also provides a compatibility layer to
> @@ -1177,11 +1180,8 @@ config OABI_COMPAT
>  	  selected, since there is no way yet to sensibly distinguish
>  	  between calling conventions during filtering.
>  
> -	  If you know you'll be using only pure EABI user space then you
> -	  can say N here. If this option is not selected and you attempt
> -	  to execute a legacy ABI binary then the result will be
> -	  UNPREDICTABLE (in fact it can be predicted that it won't work
> -	  at all). If in doubt say N.
> +	  Support for OABI_COMPAT will be removed from the kernel
> +	  once Intel StrongARM CPUs are phased out.
>  
>  config ARCH_SELECT_MEMORY_MODEL
>  	def_bool y
> diff --git a/arch/arm/configs/am200epdkit_defconfig b/arch/arm/configs/am200epdkit_defconfig
> index b3f81237c6e1..d4745b0f3dcb 100644
> --- a/arch/arm/configs/am200epdkit_defconfig
> +++ b/arch/arm/configs/am200epdkit_defconfig
> @@ -7,7 +7,6 @@ CONFIG_EXPERT=y
>  # CONFIG_ARCH_MULTI_V7 is not set
>  CONFIG_ARCH_PXA=y
>  CONFIG_ARCH_GUMSTIX=y
> -# CONFIG_OABI_COMPAT is not set
>  CONFIG_CMDLINE="console=ttyS0,115200n8 root=1f01 rootfstype=jffs2"
>  CONFIG_MODULES=y
>  CONFIG_MODULE_UNLOAD=y
> diff --git a/arch/arm/configs/axm55xx_defconfig b/arch/arm/configs/axm55xx_defconfig
> index 12c59a4ee504..541e38e2205b 100644
> --- a/arch/arm/configs/axm55xx_defconfig
> +++ b/arch/arm/configs/axm55xx_defconfig
> @@ -38,7 +38,6 @@ CONFIG_PCIE_AXXIA=y
>  CONFIG_SMP=y
>  CONFIG_NR_CPUS=16
>  CONFIG_HOTPLUG_CPU=y
> -CONFIG_OABI_COMPAT=y
>  CONFIG_HIGHMEM=y
>  CONFIG_ARM_APPENDED_DTB=y
>  CONFIG_ARM_ATAG_DTB_COMPAT=y
> diff --git a/arch/arm/configs/footbridge_defconfig b/arch/arm/configs/footbridge_defconfig
> index 589b7b1df8c6..e8bf9847d35d 100644
> --- a/arch/arm/configs/footbridge_defconfig
> +++ b/arch/arm/configs/footbridge_defconfig
> @@ -9,9 +9,9 @@ CONFIG_ARCH_MULTI_V4=y
>  CONFIG_ARCH_FOOTBRIDGE=y
>  CONFIG_ARCH_EBSA285_HOST=y
>  CONFIG_ARCH_NETWINDER=y
> +# CONFIG_AEABI is not set
>  CONFIG_FPE_NWFPE=y
>  CONFIG_FPE_NWFPE_XP=y
> -# CONFIG_AEABI is not set

I'm not objecting to the change this reordering is not directly related
to the current patch, maybe this should be squashed in 1/19

>  CONFIG_MODULES=y
>  CONFIG_PARTITION_ADVANCED=y
>  CONFIG_ACORN_PARTITION=y
> diff --git a/arch/arm/configs/neponset_defconfig b/arch/arm/configs/neponset_defconfig
> index c3010a4d93a8..16f0afd770c1 100644
> --- a/arch/arm/configs/neponset_defconfig
> +++ b/arch/arm/configs/neponset_defconfig
> @@ -6,12 +6,12 @@ CONFIG_ARCH_MULTI_V4=y
>  CONFIG_ARCH_SA1100=y
>  CONFIG_SA1100_ASSABET=y
>  CONFIG_ASSABET_NEPONSET=y
> +# CONFIG_AEABI is not set
>  CONFIG_ZBOOT_ROM_TEXT=0x80000
>  CONFIG_ZBOOT_ROM_BSS=0xc1000000
>  CONFIG_ZBOOT_ROM=y
>  CONFIG_CMDLINE="console=ttySA0,38400n8 cpufreq=221200 rw root=/dev/mtdblock2 mtdparts=sa1100:512K(boot),1M(kernel),2560K(initrd),4M(root) mem=32M noinitrd initrd=0xc0800000,3M"
>  CONFIG_FPE_NWFPE=y
> -# CONFIG_AEABI is not set

Ditto

>  CONFIG_PM=y
>  CONFIG_MODULES=y
>  CONFIG_MODULE_UNLOAD=y
> diff --git a/arch/arm/configs/versatile_defconfig b/arch/arm/configs/versatile_defconfig
> index 8e89debb5a5b..bb9eb9ccbbde 100644
> --- a/arch/arm/configs/versatile_defconfig
> +++ b/arch/arm/configs/versatile_defconfig
> @@ -6,7 +6,6 @@ CONFIG_LOG_BUF_SHIFT=14
>  CONFIG_BLK_DEV_INITRD=y
>  # CONFIG_ARCH_MULTI_V7 is not set
>  CONFIG_ARCH_VERSATILE=y
> -CONFIG_OABI_COMPAT=y
>  CONFIG_CMDLINE="root=1f03 mem=32M"
>  CONFIG_FPE_NWFPE=y
>  CONFIG_VFP=y
> -- 
> 2.39.5
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com