Re: [PATCH] scripts: subarch.include: fix SUBARCH on MacOS hosts

[Nicolas Schier <nicolas@fjasle.eu>]

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On Sun, 13 Nov 2022 15:38:09 -0800 Nick Desaulniers wrote:
> When building the Linux kernel on an aarch64 MacOS based host, if we don't
> specify a value for ARCH when invoking make, we default to arm and thus
> multi_v7_defconfig rather than the expected arm64 and arm64's defconfig.
> 
> This is because subarch.include invokes `uname -m` which on MacOS hosts
> evaluates to `arm64` but on Linux hosts evaluates to `aarch64`,
> 
> This allows us to build ARCH=arm64 natively on MacOS (as in ARCH need
> not be specified on an aarch64-based system).
> 
> Utilize a negative lookahead regular expression to avoid matching arm64.
> 
> Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
> ---
> This is only part 1 of
> https://github.com/ClangBuiltLinux/linux/commit/f06333e29addbc3d714adb340355f471c1dfe95a
> I'm still working on the rest...
> 
>  scripts/subarch.include | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/subarch.include b/scripts/subarch.include
> index 4bd327d0ae42..aa130286b627 100644
> --- a/scripts/subarch.include
> +++ b/scripts/subarch.include
> @@ -6,7 +6,7 @@
>  
>  SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
>  				  -e s/sun4u/sparc64/ \
> -				  -e s/arm.*/arm/ -e s/sa110/arm/ \
> +				  -e s/arm\(?:\(?!64\).*\)/arm/ -e s/sa110/arm/ \

On my Debian's sed, this does not match any more at all, e.g.:

  $ echo armv4 | sed -e 's/arm\(?:\(?!64\).*\)/arm/'
  armv4
.

This one works for me, but does not look such advanced:

  $ echo arm64 | sed -e '/^arm64$/!s/arm.*/arm/'
  arm64
  $ echo armv4 | sed -e '/^arm64$/!s/arm.*/arm/'
  arm
.

Kind regards,
Nicolas

>  				  -e s/s390x/s390/ \
>  				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
>  				  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \
> -- 
> 2.37.0 (Apple Git-136)

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