From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@suse.com>
Subject: Re: [PATCH 1/2] x86: during boot,
 anticipate identifying the boot cpu
Date: Mon, 25 Aug 2014 09:39:02 +0100
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References: <20140822165628.32764.15082.stgit@Solace.lan>
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To: Dario Faggioli <dario.faggioli@citrix.com>
Cc: george.dunlap@eu.citrix.com, Andrew Cooper <andrew.cooper3@citrix.com>, keir@xen.org, xen-devel <xen-devel@lists.xenproject.org>
List-Id: xen-devel@lists.xenproject.org

>>> On 22.08.14 at 19:15, <dario.faggioli@citrix.com> wrote:
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1262,6 +1262,12 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>  
>      timer_init();
>  
> +    /*
> +     * Identify the boot CPU, in case the scheduler initialization
> +     * needs to know about it (e.g., topology, etc.)
> +     */
> +    identify_cpu(&boot_cpu_data);
> +
>      init_idle_domain();
>  
>      trap_init();
> @@ -1272,8 +1278,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>  
>      arch_init_memory();
>  
> -    identify_cpu(&boot_cpu_data);
> -
>      if ( cpu_has_fxsr )
>          set_in_cr4(X86_CR4_OSFXSR);
>      if ( cpu_has_xmm )

I'm not sure about this part: It currently makes quite a bit of sense
to have identify_cpu() immediately before explicit users of the
gathered data (all code following up to the alternative_instructions()
call). Perhaps if you move identify_cpu(), all the others should get
moved too?

Jan