Re: [PATCH v3 3/5] selftests/nolibc: add s390 support

[Heiko Carstens]

On Tue, Jan 03, 2023 at 08:19:55AM +0100, Sven Schnelle wrote:
> Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
> Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
> ---
>  tools/testing/selftests/nolibc/Makefile | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
...
> -CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables
> +CFLAGS_s390 = -m64
> +CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables $(CFLAGS_$(ARCH))

Since this adds support for architecture specific compile flags, you
might as well want to add -march=z10, since that's the minimum
architecture level for the kernel we support anyway.

That way you won't end up with problems like the lay instruction, and
could also use cghsi for zero comparison. Not that I'm proposing that
you should change the asm code again, it is fine as it is now.