linux-kernel - Re: [PATCH v2 1/1] x86: Use x2apic physical mode based on FADT setting

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Message-ID: <1335318345.28674.268.camel@sbsiddha-desk.sc.intel.com>
Date:	Tue, 24 Apr 2012 18:45:45 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Greg Pearson <greg.pearson@...com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] x86: Use x2apic physical mode based on FADT
 setting

On Tue, 2012-04-24 at 18:23 -0600, Greg Pearson wrote:
> Provide systems that do not support x2apic cluster mode
> a mechanism to select x2apic physical mode using the
> FADT FORCE_APIC_PHYSICAL_DESTINATION_MODE bit.
> 
> Changes from v1: (based on Suresh's comments)
> - removed #ifdef CONFIG_ACPI
> - removed #include <linux/acpi.h>
> 
> Signed-off-by: Greg Pearson <greg.pearson@...com>
> ---
>  arch/x86/kernel/apic/x2apic_phys.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
> index 8a778db..991e315 100644
> --- a/arch/x86/kernel/apic/x2apic_phys.c
> +++ b/arch/x86/kernel/apic/x2apic_phys.c
> @@ -24,6 +24,12 @@ static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>  {
>  	if (x2apic_phys)
>  		return x2apic_enabled();
> +	else if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) &&
> +		(acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) &&
> +		x2apic_enabled()) {
> +		printk(KERN_DEBUG "System requires x2apic physical mode\n");
> +		return 1;
> +	}
>  	else
>  		return 0;
>  }

Acked-by: Suresh Siddha <suresh.b.siddha@...el.com>

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