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SubjectRe: [Xen-devel] [PATCHv1] x86: rtc_cmos platform device requires legacy irqs
On 03/12/15 10:43, David Vrabel wrote:
> Adding the rtc platform device when there are no legacy irqs (no
> legacy PIC) causes a conflict with other devices that end up using the
> same irq number.

An alternative is to remove the rtc_cmos platform device in Xen PV
guests.

Any preference on how this regression should be fixed?

David

8<--------------------------
x86: Xen PV guests don't have the rtc_cmos platform device

Adding the rtc platform device in a Xen PV guests causes an IRQ
conflict because these guests do not have a legacy PIC.

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)

So don't add the rtc_cmos device in Xen PV guests.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
---
arch/x86/kernel/rtc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index cd96852..7b190b8 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -200,6 +200,9 @@ static __init int add_rtc_cmos(void)
}
#endif

+ if (xen_pv_domain())
+ return -ENODEV;
+
platform_device_register(&rtc_device);
dev_info(&rtc_device.dev,
"registered platform RTC device (no PNP device found)\n");
--
2.1.4


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