Re: [Xen-devel] [PATCH] x86/boot: copy/clear sections more efficiently

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.06.16 at 11:58, <andrew.cooper3@xxxxxxxxxx> wrote:

> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -128,7 +128,8 @@ __start:
>          mov     $sym_phys(__bss_end),%ecx
>          sub     %edi,%ecx
>          xor     %eax,%eax
> -        rep     stosb
> +        shr     $2,%ecx
> +        rep     stosl

Please take the opportunity and reduce the whitespace between
prefix and instruction to just one (to make clear "rep" is not the
instruction and "stosl" is not it operand).

> @@ -192,8 +193,8 @@ __start:
>  
>          /* Copy bootstrap trampoline to low memory, below 1MB. */
>          mov     $sym_phys(trampoline_start),%esi
> -        mov     $trampoline_end - trampoline_start,%ecx
> -        rep     movsb
> +        mov     $((trampoline_end - trampoline_start) / 4),%ecx
> +        rep     movsl

Same here.

With that
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>


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