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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 24 Apr 2012 15:53:26 -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 1/1] x86: Use x2apic physical mode based on FADT setting

On Tue, 2012-04-24 at 16:38 -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.
> 
> Signed-off-by: Greg Pearson <greg.pearson@...com>
> ---
>  arch/x86/kernel/apic/x2apic_phys.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
> index 8a778db..c372926 100644
> --- a/arch/x86/kernel/apic/x2apic_phys.c
> +++ b/arch/x86/kernel/apic/x2apic_phys.c
> @@ -6,6 +6,10 @@
>  #include <linux/init.h>
>  #include <linux/dmar.h>
>  
> +#ifdef CONFIG_ACPI
> +#include <linux/acpi.h>
> +#endif

dmar.h already includes acpi.h

> +
>  #include <asm/smp.h>
>  #include <asm/x2apic.h>
>  
> @@ -24,6 +28,14 @@ static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
>  {
>  	if (x2apic_phys)
>  		return x2apic_enabled();
> +#ifdef CONFIG_ACPI
> +	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;
> +	}
> +#endif

x2apic is already dependent on irq-remapping which depends on ACPI. So I
think you can do away with those ifdef CONFIG_ACPI.

Also, which system requires this? If you can include the information in
the changelog that will be great.

thanks,
suresh

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/