[PATCH 2/3] scripts: Select XZ --arm64 BCJ filter for 64-bit arm

[Ahmad Fatoum]

On 06.09.23 17:08, Jules Maselbas wrote:
> This change will select the arm64 BCJ filter for aarch64 instead of
> the arm filter which was always selected for arm based architectures.
> 
> The selected filter is also tested, by looking if it is present in
> the long help message of xz, this is because the arm64 BCJ filter is
> a recent addition to xz.
> 
> Signed-off-by: Jules Maselbas <jmaselbas at zdiv.net>

How much of an improvement is BCJ=--arm over BCJ=""?

I wonder if we should fallback from --arm64 to --arm.

Cheers,
Ahmad

> ---
>  scripts/xz_wrap.sh | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/xz_wrap.sh b/scripts/xz_wrap.sh
> index 7a2d372f48..5b5f3adcff 100755
> --- a/scripts/xz_wrap.sh
> +++ b/scripts/xz_wrap.sh
> @@ -16,8 +16,11 @@ case $SRCARCH in
>  	x86)            BCJ=--x86 ;;
>  	powerpc)        BCJ=--powerpc ;;
>  	ia64)           BCJ=--ia64; LZMA2OPTS=pb=4 ;;
> -	arm)            BCJ=--arm ;;
> +	arm)            BCJ=--arm$S64 ;;
>  	sparc)          BCJ=--sparc ;;
>  esac
>  
> +# clear BCJ filter if unsupported
> +xz -H | grep -q -- $BCJ || BCJ=
> +
>  exec xz --check=crc32 $BCJ --lzma2=$LZMA2OPTS,dict=32MiB

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