Re: [Xen-devel] [patch] x86: Add a delay between INIT & SIPIs for AP bring-up in X2APIC case

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.12.11 at 12:22, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote:
> Without this delay, Xen could not bring APs up while working with TXT/tboot, 
> because tboot need some time in APs to handle INIT before becoming ready for 
> receiving SIPIs. (this delay was removed as part of c/s 23724 by Tim Deegan)
> 
> Signed-off-by: Gang Wei <gang.wei@xxxxxxxxx>
> 
> diff -r d1aefee43af1 xen/arch/x86/smpboot.c
> --- a/xen/arch/x86/smpboot.c    Wed Dec 21 18:51:31 2011 +0800
> +++ b/xen/arch/x86/smpboot.c    Wed Dec 21 19:08:57 2011 +0800
> @@ -463,6 +463,10 @@ static int wakeup_secondary_cpu(int phys
>              send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
>          } while ( send_status && (timeout++ < 1000) );
>      }
> +    else
> +    {
> +        mdelay(10);
> +    }

Does it really need to be this long then (even in the non-TBOOT
case)?

Jan

> 
>      /*
>       * Should we send STARTUP IPIs ?




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