Messages in this thread | | | Subject | Re: [Xen-devel] [PATCH] x86: Xen PV guests don't have the rtc_cmos platform device | From | Boris Ostrovsky <> | Date | Wed, 9 Dec 2015 13:18:57 -0500 |
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On 12/09/2015 10:27 AM, Jan Beulich wrote: >>>> On 09.12.15 at 16:15, <boris.ostrovsky@oracle.com> wrote: >> On 12/09/2015 10:00 AM, Sander Eikelenboom wrote: >>> On 2015-12-09 15:42, Jan Beulich wrote: >>>>>>> On 09.12.15 at 15:32, <boris.ostrovsky@oracle.com> wrote: >>>>> --- 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 (paravirt_enabled()) >>>>> + return -ENODEV; >>>> What about Xen Dom0? >>>> >>>> Jan >>> Checked that in my testing and that still worked: >>> [ 16.733837] rtc_cmos 00:02: RTC can wake from S4 >>> [ 16.734030] rtc_cmos 00:02: rtc core: registered rtc_cmos as rtc0 >>> [ 16.734087] rtc_cmos 00:02: alarms up to one month, y3k, 114 bytes >>> nvram >>> [ 17.760329] rtc_cmos 00:02: setting system clock to 2015-12-09 >>> 08:43:48 UTC (1449650628) >>> >>> and /dev/rtc and /dev/rtc0 both exist. >>> >>> But i don't know the nitty gritty details about why ... >> >> That's because it is discovered by ACPI earlier. I don't know though >> whether we can always assume this will be the case. > I don't think we should - Dom0 should (device-wise) behave just > like a native kernel.
So maybe then this is the case for having a feature flag (probably in pv_info) that marks which features are paravirtualized.
Vitaly suggested it earlier but I thought we won't have use for it until we get to HVMlite with variable set of fetures.
-boris
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