From: Gleb Natapov <gleb@kernel.org>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86 <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH] x86: Make x2APIC support depend on interrupt remapping or guest support
Date: Sun, 6 Jul 2014 18:12:42 +0300 [thread overview]
Message-ID: <20140706151242.GN18167@minantech.com> (raw)
In-Reply-To: <53B7ADAA.9030101@web.de>
On Sat, Jul 05, 2014 at 09:47:54AM +0200, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
>
> We are able to use x2APIC mode in the absence of interrupt remapping on
> certain hypervisors. So it if fine to disable IRQ_REMAP without having
> to give up x2APIC support.
FWIW I did similar thing back when I added x2apic to KVM:
http://linux.derkeiler.com/Mailing-Lists/Kernel/2009-06/msg14579.html
But was advised against it.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> arch/x86/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a8f749e..30a9987 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -310,7 +310,7 @@ config SMP
>
> config X86_X2APIC
> bool "Support x2apic"
> - depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
> + depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
> ---help---
> This enables x2apic support on CPUs that have this feature.
>
>
>
--
Gleb.
next prev parent reply other threads:[~2014-07-06 15:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-05 7:47 [PATCH] x86: Make x2APIC support depend on interrupt remapping or guest support Jan Kiszka
2014-07-06 14:32 ` Paolo Bonzini
2014-07-06 15:12 ` Gleb Natapov [this message]
2014-07-06 15:24 ` Jan Kiszka
2014-07-06 15:41 ` Gleb Natapov
2014-07-06 15:49 ` Jan Kiszka
2014-07-06 17:28 ` Gleb Natapov
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