On 06/01/2026 03:06, Keith Packard wrote:
> The arm multilib configuration includes two more parameters which
> affect multilib selection, marm/mthumb and mfloat-abi. Without those,
> the default multilib selection is mis-specified and the only reason it
> works is because '.' is the fall-back path.
> 
> Add "marm" and "mfloat-abi=soft" to MULTILIB_DEFAULTS to actually
> match when the compiler is run without any target parameters.
> 
> This hasn't caused any problems in practice because there are no
> non-default multilib options which can be applied to the default
> -march target as it has neither an FPU nor any branch protection
> support. Specifying another cpu or architecture always sets -marm and
> -mfloat-abi and so those multilib configuration don't rely on the
> defaults.
> 
> Signed-off-by: Keith Packard <[email protected]>
> ---
>  gcc/config/arm/arm-mlib.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gcc/config/arm/arm-mlib.h b/gcc/config/arm/arm-mlib.h
> index 01a8421e20f..082476318c7 100644
> --- a/gcc/config/arm/arm-mlib.h
> +++ b/gcc/config/arm/arm-mlib.h
> @@ -19,4 +19,4 @@
>     along with GCC; see the file COPYING3.  If not see
>     <http://www.gnu.org/licenses/>.  */
>  
> -#define MULTILIB_DEFAULTS { "mbranch-protection=none" }
> +#define MULTILIB_DEFAULTS { "marm", "mfloat-abi=soft", 
> "mbranch-protection=none",  }

Hi Keith,

Can you supply a bit more background for this please?  Is there a problem that 
you're trying to solve, for example, or is it simply based on observation?

I suspect that if this is right, then you probably also need "mfpu=auto" in the 
defaults as well, for example.  There may be others too.

R.

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