[U-Boot] [PATCH v2 34/63] x86: Support global_data on x86_64

[Bin Meng]

Hi Simon,

On Sun, Nov 20, 2016 at 4:25 AM, Simon Glass <sjg at chromium.org> wrote:
> At present this is just an ordinary variable. We may consider making it a
> fixed register in the future.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v2: None
>
>  arch/x86/cpu/x86_64/cpu.c          | 13 +++++++++++++
>  arch/x86/include/asm/global_data.h |  6 +++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/cpu/x86_64/cpu.c b/arch/x86/cpu/x86_64/cpu.c
> index c1d3788..da2ad11 100644
> --- a/arch/x86/cpu/x86_64/cpu.c
> +++ b/arch/x86/cpu/x86_64/cpu.c
> @@ -8,6 +8,19 @@
>  #include <common.h>
>  #include <debug_uart.h>
>
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +/* Global declaration of gd */
> +struct global_data *global_data_ptr;
> +
> +void arch_setup_gd(gd_t *new_gd)
> +{
> +       global_data_ptr = new_gd;
> +
> +       /* TODO(sjg at chromium.org): Why is this needed? */

What happens if this is not needed? Can you explain a little bit about the TODO?

> +       printch(' ');
> +}
> +
>  int cpu_has_64bit(void)
>  {
>         return true;
> diff --git a/arch/x86/include/asm/global_data.h b/arch/x86/include/asm/global_data.h
> index 7434f77..ce9e5cc 100644
> --- a/arch/x86/include/asm/global_data.h
> +++ b/arch/x86/include/asm/global_data.h
> @@ -104,7 +104,7 @@ struct arch_global_data {
>  #include <asm-generic/global_data.h>
>
>  #ifndef __ASSEMBLY__
> -# ifdef CONFIG_EFI_APP
> +# if defined(CONFIG_EFI_APP) || CONFIG_IS_ENABLED(X86_64)
>
>  #define gd global_data_ptr
>
> @@ -114,7 +114,11 @@ static inline __attribute__((no_instrument_function)) gd_t *get_fs_gd_ptr(void)
>  {
>         gd_t *gd_ptr;
>
> +#if CONFIG_IS_ENABLED(X86_64)
> +       asm volatile("fs mov 0, %0\n" : "=r" (gd_ptr));
> +#else
>         asm volatile("fs movl 0, %0\n" : "=r" (gd_ptr));
> +#endif

Can both of them be consolidated as one: asm volatile("fs mov 0, %0\n"
: "=r" (gd_ptr));

>
>         return gd_ptr;
>  }
> --

Regards,
Bin