Re: [PATCH] x86: drop XSAVEOPT and CLWB build flags

[Alexander Merritt <alexander@edera.dev>]

On 2025-04-03 19:34, Andrew Cooper wrote:
> On 04/04/2025 12:28 am, Andrew Cooper wrote:
> Also, I forgot to write in the ticket, clflushopt wants similar
> treatment, even if there isn't an outward define for it.  I think the
> following two hunks should do:
> 
> ~Andrew
> 
> diff --git a/xen/arch/x86/flushtlb.c b/xen/arch/x86/flushtlb.c
> index 18748b2bc805..ef30ef546336 100644
> --- a/xen/arch/x86/flushtlb.c
> +++ b/xen/arch/x86/flushtlb.c
> @@ -287,7 +287,7 @@ void cache_flush(const void *addr, unsigned int 
> size)
>           * of letting the alternative framework fill the gap by
> appending nops.
>           */
>          alternative_io("ds; clflush %[p]",
> -                       "data16 clflush %[p]", /* clflushopt */
> +                       "clflushopt %[p]",

Agree on these changes. However, I see branch staging uses 
alternative_input and the below /* no outputs */ does not exist.

>                         X86_FEATURE_CLFLUSHOPT,
>                         /* no outputs */,
>                         [p] "m" (*(const char *)(addr)));
> diff --git a/xen/arch/x86/include/asm/system.h
> b/xen/arch/x86/include/asm/system.h
> index 73cb16ca68d6..6f5b6d502911 100644
> --- a/xen/arch/x86/include/asm/system.h
> +++ b/xen/arch/x86/include/asm/system.h
> @@ -23,7 +23,7 @@ static inline void clflush(const void *p)
>  
>  static inline void clflushopt(const void *p)
>  {
> -    asm volatile ( "data16 clflush %0" :: "m" (*(const char *)p) );
> +    asm volatile ( "clflushopt %0" :: "m" (*(const char *)p) );
>  }
>  
>  static inline void clwb(const void *p)