Re: commit 3661261f breaks arm64

[Andrei Borzenkov]

В Wed, 28 Jan 2015 18:33:59 +0000
Leif Lindholm <address@hidden> пишет:

> commit 3661261fe17a8fe19681073889b5b36ec1ee823d,
> "Always add -msoft-float to avoid compiler generating float
> arithmetics." breaks the arm64 build.
> 
> -msoft-float is not a valid command line option for aarch64 (as far as
> I can see, it is technically a target-specific option which just
> happens to exist for most targets - including arm).
> 
> This setting will need to be conditionalised somehow.
> An option that works for arm64 is -march=armv8-a+nofp+nosimd.
> 
> Would something like this be an acceptable workaround?:
> 
> diff --git a/configure.ac b/configure.ac
> index a3bca06..c99e1ea 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -678,7 +678,11 @@ fi
>  # that floats are a good fit to run instead of what's written in the
>  # code.
>  # Given that floating point unit is disabled (if present to begin
>  # with)
>  # when GRUB is running which may result in various hard crashes.
> -TARGET_CFLAGS="$TARGET_CFLAGS -msoft-float"
> +if ( test "x$target_cpu" = xarm64 ); then

Why subshell?

> +  TARGET_CFLAGS="$TARGET_CFLAGS -march=armv8-a+nofp+nosimd"
> +else
> +  TARGET_CFLAGS="$TARGET_CFLAGS -msoft-float"
> +fi
>  
>  # By default, GCC 4.4 generates .eh_frame sections containing unwind
>  # information in some cases where it previously did not. GRUB doesn't
>  # need
> 
> /
>     Leif
> 
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