[PATCH v3 09/12] x86: Enable SSE in 64-bit mode

[Bin Meng]

+ Tom,

Hi Simon,

On Mon, Nov 6, 2023 at 12:29 AM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Bin,
>
> On Sun, 5 Nov 2023 at 14:05, Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > Hi Simon,
> >
> > On Mon, Oct 2, 2023 at 9:15 AM Simon Glass <sjg at chromium.org> wrote:
> > >
> > > This is needed to support Truetype fonts. In any case, the compiler
> > > expects SSE to be available in 64-bit mode. Enable it.
> > >
> > > Signed-off-by: Simon Glass <sjg at chromium.org>
> > > Suggested-by: Bin Meng <bmeng.cn at gmail.com>
> > > ---
> > >
> > > (no changes since v1)
> > >
> > >  arch/x86/config.mk        |  1 -
> > >  arch/x86/cpu/x86_64/cpu.c | 11 +++++++++++
> > >  2 files changed, 11 insertions(+), 1 deletion(-)
> > >
> >
> > I didn't suggest we enable SSE for x86. This is the wrong approach.
> >
> > We should rewrite the Truetype support codes to avoid using float/double types.
> >
> > This way the Truetype codes can be used on any other architectures
> > without the need for the compiler to emit explicit floating
> > instructions.
>
> I am not aware of any such library. At present, enabling truetype on
> coreboot64 causes a hang.
>

If that's the case, we will have to either:

- Switch all U-Boot builds' to use software float (e.g. -msoft-float)
which unfortunately depends on the compiler runtime intrinsics.
- Introduce a Kconfig option for hard float enabling and let each
architecture to decide whether it implements it or not, and update
Truetype to depend on the hard float.

Regards,
Bin