linux-kernel - Re: [Xen-devel] [PATCHv1] x86: rtc_cmos platform device requires legacy irqs

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Message-ID: <87io4e5hz4.fsf@vitty.brq.redhat.com>
Date:	Fri, 04 Dec 2015 16:52:31 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:	David Vrabel <david.vrabel@...rix.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, xen-devel@...ts.xenproject.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Xen-devel] [PATCHv1] x86: rtc_cmos platform device requires legacy irqs

Boris Ostrovsky <boris.ostrovsky@...cle.com> writes:

> On 12/04/2015 10:24 AM, David Vrabel wrote:
>> On 04/12/15 14:06, David Vrabel wrote:
>>> 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
>>>
>> [...]
>>> --- 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;
>>> +
>> Note there's a missing include that breaks !XEN builds.
>
> We could also use paravirt_enable() here which will probably cover
> HVMlite case as well. (Until we start turning on and off various
> HVMlite features).

Would it make sense to create a new abstraction, e.g. 'rtc_available' in
struct hypervisor_x86?

-- 
  Vitaly
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