Re: [PATCH v2] xen/arm64: Add support Clang build on arm64

[Saman Dehghan <samaan.dehghan@xxxxxxxxx>]

On Thu, Dec 11, 2025 at 3:35 AM Julien Grall <julien@xxxxxxx> wrote:
>
>
>
> On 11/12/2025 02:39, Saman Dehghan wrote:
> > This patch enables building Xen on arm64 architecture using the Clang 
> > compiler.
> > Changes include:
> > - Add explicit -march=armv8 flag for arm64 builds.
> > - Add `__attribute__((target("fp-armv8")))` to `vfp_save_state` and
> >    `vfp_restore_state` functions when building with Clang to allow
> >    FP instructions despite `-mgeneral-regs-only`.
> >
> > Signed-off-by: Saman Dehghan <samaan.dehghan@xxxxxxxxx>
> > ---
> >   README                   | 2 ++
> >   xen/arch/arm/arch.mk     | 1 +
> >   xen/arch/arm/arm64/vfp.c | 6 ++++++
> >   3 files changed, 9 insertions(+)
> >
> > diff --git a/README b/README
> > index 889a4ea906..67c1aa7fe6 100644
> > --- a/README
> > +++ b/README
> > @@ -45,6 +45,8 @@ provided by your OS distributor:
> >         - For ARM:
> >           - GCC 5.1 or later
> >           - GNU Binutils 2.25 or later
> > +        or
> > +        - Clang/LLVM 11 or later
>
> I forgot to ask. Is this cross-compiling or native? Or both?
>
> And OOI, how did you chose Clang 11?

Hi Julien,

To be consistent with minimum requirements for Clang/LLVM on x86.

~Saman

>
> Cheers,
>
> --
> Julien Grall
>