Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759845AbbLCLYA (ORCPT ); Thu, 3 Dec 2015 06:24:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40575 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751677AbbLCLX7 (ORCPT ); Thu, 3 Dec 2015 06:23:59 -0500 From: Vitaly Kuznetsov To: David Vrabel Cc: , linux-kernel@vger.kernel.org, Ingo Molnar , "H. Peter Anvin" , xen-devel@lists.xenproject.org, Thomas Gleixner , Boris Ostrovsky Subject: Re: [Xen-devel] [PATCHv1] x86: rtc_cmos platform device requires legacy irqs References: <1449139404-25101-1-git-send-email-david.vrabel@citrix.com> Date: Thu, 03 Dec 2015 12:23:55 +0100 In-Reply-To: <1449139404-25101-1-git-send-email-david.vrabel@citrix.com> (David Vrabel's message of "Thu, 3 Dec 2015 10:43:24 +0000") Message-ID: <87mvtr7p2s.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2481 Lines: 75 David Vrabel writes: > Adding the rtc platform device when there are no legacy irqs (no > legacy PIC) No PIC != No legacy IRQs, Hyper-V Gen2 represents such a platform (and it has RTC on irq8). I've tested this patch against it and it appears to work because the device is present in ACPI and we initialize it in drivers/acpi/acpi_cmos_rtc.c, add_rtc_cmos() bails out in the very beginning as we see PNP0b00 device. > causes a conflict with other devices that end up using the > same irq number. > > In a single VCPU Xen PV guest we should have: > > /proc/interrupts: > CPU0 > 0: 4934 xen-percpu-virq timer0 > 1: 0 xen-percpu-ipi spinlock0 > 2: 0 xen-percpu-ipi resched0 > 3: 0 xen-percpu-ipi callfunc0 > 4: 0 xen-percpu-virq debug0 > 5: 0 xen-percpu-ipi callfuncsingle0 > 6: 0 xen-percpu-ipi irqwork0 > 7: 321 xen-dyn-event xenbus > 8: 90 xen-dyn-event hvc_console > ... > > But hvc_console cannot get its interrupt because it is already in use > by rtc0 and the console does not work. > > genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0) > > The rtc_cmos device requires a particular legacy irq so don't add it > if there are no legacy irqs. > > Reported-by: Sander Eikelenboom > Signed-off-by: David Vrabel > Tested-by: Sander Eikelenboom > --- > arch/x86/kernel/rtc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c > index cd96852..07c70f1 100644 > --- a/arch/x86/kernel/rtc.c > +++ b/arch/x86/kernel/rtc.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_X86_32 > /* > @@ -200,6 +201,10 @@ static __init int add_rtc_cmos(void) > } > #endif > > + /* RTC uses legacy IRQs. */ > + if (!nr_legacy_irqs()) > + return -ENODEV; > + > platform_device_register(&rtc_device); > dev_info(&rtc_device.dev, > "registered platform RTC device (no PNP device found)\n"); -- Vitaly -- 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/