From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 2/2] acpi: Disable IRQ 0 through I/O APIC for some HP systems Date: Mon, 7 Jul 2008 20:03:47 +0200 Message-ID: <200807072003.48228.rjw@sisk.pl> References: <200807071423.48425.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: "Maciej W. Rozycki" Cc: Ingo Molnar , Matthew Garrett , Len Brown , Thomas Gleixner , linux-next@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Andi Kleen List-Id: linux-next.vger.kernel.org On Monday, 7 of July 2008, Maciej W. Rozycki wrote: > On Mon, 7 Jul 2008, Rafael J. Wysocki wrote: > > > > It makes absolutely no sense and should be harmful to call > > > clear_IO_APIC_pin(apic1, pin1) here, because both apic1 and pin1 should be > > > equal to -1 here. If it has to be called, then I suppose the DMI matching > > > did not work and the workaround has not been enabled. > > > > Do you realize that the clear_IO_APIC_pin(apic1, pin1) thing is _only_ called > > _IF_ the DMI matching did work? > > Well, it is the very intent of the DMI quirk to set apic1 and pin1 both > to -1, as a result of IRQ0 being absent from our I/O APIC interrupt > routing table. Therefore if the quirk did indeed work, a call to > clear_IO_APIC_pin() is useless and likely harmful as its callees don't do > range checking (my understanding of code is it results in random poking at > the local APIC through the FIX_APIC_BASE fixmap). There should be nothing > to clear too, as interrupt redirection entries for all the I/O APIC inputs > are cleared (the mask is set to 1 and the remaining fields zeroed) when > clear_IO_APIC() is called from enable_IO_APIC() upon initialization and > all the unused ones (not referred to from anywhere in the interrupt > routing table) are never touched afterwards. Sorry, the patch I posted was _instead_ of your previous patch with the quirk, because that patch didn't work. I don't know why it didn't work, however, I can only say it didn't work after removing the __i386__ dependency of acpi_dmi_table[]. My patch is on top of the linux-next tree that didn't contain your patch. So, my patch adds a quirk that sets disable_irq0_through_ioapic to 1 (this variable is defined differently in my patch) and uses it to skip the part of check_timer() that breaks my box. I hope that makes things clear. Thanks, Rafael