Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932468Ab1COROA (ORCPT ); Tue, 15 Mar 2011 13:14:00 -0400 Received: from s15228384.onlinehome-server.info ([87.106.30.177]:34255 "EHLO mail.x86-64.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932357Ab1CORN7 (ORCPT ); Tue, 15 Mar 2011 13:13:59 -0400 From: Boris Ostrovsky To: hpa@zytor.com, mingo@elte.hu, tglx@linutronix.de Cc: borislav.petkov@amd.com, andreas.herrmann3@amd.com, mark.langsdorf@amd.com, linux-kernel@vger.kernel.org, Boris Ostrovsky Subject: [PATCH RESEND] x86, AMD: Set ARAT feature on AMD processors Date: Tue, 15 Mar 2011 12:13:44 -0400 Message-Id: <1300205624-4813-1-git-send-email-ostr@amd64.org> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1561 Lines: 43 From: Boris Ostrovsky Support for Always Running APIC timer (ARAT) was introduced in commit db954b5898dd3ef3ef93f4144158ea8f97deb058. This feature allows us to avoid switching timers from LAPIC to something else (e.g. HPET) and go into timer broadcasts when entering deep C-states. AMD processors don't provide a CPUID bit for that feature but they also keep APIC timers running in deep C-states (except for cases when the processor is affected by erratum 400). Therefore we should set ARAT feature bit on AMD CPUs. Signed-off-by: Boris Ostrovsky Tested-by: Borislav Petkov Acked-by: Andreas Herrmann Acked-by: Mark Langsdorf --- arch/x86/kernel/cpu/amd.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 7c7bedb..48eaa1b 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -594,6 +594,10 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c) } } #endif + + /* As a rule processors have APIC timer running in deep C states */ + if (c->x86 >= 0xf && !cpu_has_amd_erratum(amd_erratum_400)) + set_cpu_cap(c, X86_FEATURE_ARAT); } #ifdef CONFIG_X86_32 -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/