From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751953AbYGAFHG (ORCPT ); Tue, 1 Jul 2008 01:07:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750945AbYGAFGy (ORCPT ); Tue, 1 Jul 2008 01:06:54 -0400 Received: from agminet01.oracle.com ([141.146.126.228]:46268 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbYGAFGx (ORCPT ); Tue, 1 Jul 2008 01:06:53 -0400 Date: Mon, 30 Jun 2008 21:57:46 -0700 From: Randy Dunlap To: "Maciej W. Rozycki" Cc: Ingo Molnar , Matthew Garrett , "Rafael J. Wysocki" , Len Brown , Thomas Gleixner , linux-next@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mpparse: Add a knob to disable IRQ 0 through I/O APIC Message-Id: <20080630215746.84ffb0f4.randy.dunlap@oracle.com> In-Reply-To: References: Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.12.0; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 1 Jul 2008 01:11:35 +0100 (BST) Maciej W. Rozycki wrote: > As discovered recently some systems exhibit problems when the 8254 timer > IRQ is routed through the I/O APIC. These problems do not affect the > timer IRQ itself and therefore cannot be detected when the correctness of > operation of the interrupt is verified in check_timer(). Therefore the > I/O APIC path of the timer IRQ has to be disabled entirely. > > This is a change that lets platforms ask for the timer IRQ not to be > registered in the I/O APIC interrupt tables. The local APIC and ExtINTA > paths are unaffected. This request is only taken into account for ACPI > platforms as MP table systems seem unaffected so far. > > Signed-off-by: Maciej W. Rozycki > --- > patch-2.6.26-rc1-20080505-mpparse-acpi-noirq0-2 > diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/arch/x86/kernel/mpparse.c linux-2.6.26-rc1-20080505/arch/x86/kernel/mpparse.c > --- linux-2.6.26-rc1-20080505.macro/arch/x86/kernel/mpparse.c 2008-05-05 02:56:19.000000000 +0000 > +++ linux-2.6.26-rc1-20080505/arch/x86/kernel/mpparse.c 2008-06-30 21:53:33.000000000 +0000 > @@ -50,6 +50,8 @@ static int mp_current_pci_id; > > int pic_mode; > > +int disable_irq0_through_ioapic __initdata; > + > /* > * Intel MP BIOS table parsing routines: > */ > @@ -887,6 +889,10 @@ void __init mp_override_legacy_irq(u8 bu > int ioapic = -1; > int pin = -1; > > + /* Skip the 8254 timer interrupt (IRQ 0) if requested. */ > + if (bus_irq == 0 && disable_irq0_through_ioapic) > + return; > + > /* > * Convert 'gsi' to 'ioapic.pin'. > */ > @@ -955,6 +961,10 @@ void __init mp_config_acpi_legacy_irqs(v > for (i = 0; i < 16; i++) { > int idx; > > + /* Skip the 8254 timer interrupt (IRQ 0) if requested. */ > + if (i == 0 && disable_irq0_through_ioapic) > + continue; > + > for (idx = 0; idx < mp_irq_entries; idx++) { > struct mpc_config_intsrc *irq = mp_irqs + idx; > > diff -up --recursive --new-file linux-2.6.26-rc1-20080505.macro/include/asm-x86/mpspec.h linux-2.6.26-rc1-20080505/include/asm-x86/mpspec.h > --- linux-2.6.26-rc1-20080505.macro/include/asm-x86/mpspec.h 2008-05-05 02:55:57.000000000 +0000 > +++ linux-2.6.26-rc1-20080505/include/asm-x86/mpspec.h 2008-06-30 22:29:23.000000000 +0000 > @@ -113,4 +113,15 @@ typedef struct physid_mask physid_mask_t > > extern physid_mask_t phys_cpu_present_map; > > +#ifdef CONFIG_X86_MPPARSE > +static inline void set_disable_irq0_through_ioapic(int v) > +{ > + extern int disable_irq0_through_ioapic; > + > + disable_irq0_through_ioapic = v; > +} > +#else > +static inline void set_disable_irq0_through_ioapic(int v) { } > +#endif > + > #endif What calls set_disable_irq0_through_ioapic() ? --- ~Randy Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA http://linuxplumbersconf.org/