Re: [PATCH] configure: Check whether we can compile the s390-ccw bios with -msoft-float

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 25 May 2021 16:20:32 +0200
Thomas Huth <thuth@redhat.com> wrote:

> The -msoft-float switch is not available in older versions of Clang.
> Since we rely on the compiler to not generate floating point instructions
> unexpectedly, we block those old compilers now via a test in the configure
> script. Note that for some weird reasons, the Clang compiler only complains
> about the missing soft-float support if no other flags are passed via
> "-Wl,..." to the linker. So we have to use "compile_object" instead of
> "compile_prog" for this check.

Ugh.

> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  configure | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 676239c697..673419ff31 100755
> --- a/configure
> +++ b/configure
> @@ -5462,7 +5462,7 @@ if test "$cpu" = "s390x" ; then
>    write_c_skeleton
>    compile_prog "-march=z900" ""
>    has_z900=$?
> -  if [ $has_z900 = 0 ] || compile_prog "-march=z10" ""; then
> +  if [ $has_z900 = 0 ] || compile_object "-march=z10 -msoft-float -Werror"; then

Do you believe that we should have caught the various clang
specialties now?

>      if [ $has_z900 != 0 ]; then
>        echo "WARNING: Your compiler does not support the z900!"
>        echo "         The s390-ccw bios will only work with guest CPUs >= z10."