Does XEN ARM support RTC in domu?

Does XEN ARM support RTC in domu?

[Peng Fan]

Hi All,

Just have a question, does XEN ARM support RTC in domu? To support Android in DomU, RTC is needed for alarm, but I did not find information about RTC on xen for domu. So this need a new RTC paravirtualization driver? Any suggestions?

Thanks,
Peng.

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Re: Does XEN ARM support RTC in domu?

[Julien Grall]

On 10/31/18 1:57 PM, Peng Fan wrote:
> Hi All,

Hi,

> 
> Just have a question, does XEN ARM support RTC in domu? To support Android in DomU, RTC is needed for alarm, but I did not find information about RTC on xen for domu. So this need a new RTC paravirtualization driver? Any suggestions?

By RTC, do you mean Real-Time Clock? Something like PL031? Or do you 
have something else in mind?

Cheers,

-- 
Julien Grall

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Re: Does XEN ARM support RTC in domu?

[Peng Fan]

Hi Julien,

> -----Original Message-----
> From: Julien Grall [mailto:julien.grall@arm.com]
> Sent: 2018年11月1日 2:52
> To: Peng Fan <peng.fan@nxp.com>; xen-devel@lists.xenproject.org; Stefano
> Stabellini <sstabellini@kernel.org>
> Subject: Re: Does XEN ARM support RTC in domu?
> 
> 
> 
> On 10/31/18 1:57 PM, Peng Fan wrote:
> > Hi All,
> 
> Hi,
> 
> >
> > Just have a question, does XEN ARM support RTC in domu? To support Android
> in DomU, RTC is needed for alarm, but I did not find information about RTC on
> xen for domu. So this need a new RTC paravirtualization driver? Any suggestions?
> 
> By RTC, do you mean Real-Time Clock? Something like PL031? Or do you have
> something else in mind?

Yes, Real Time Clock like PL031 in DomU. I do not have a good idea support RTC in ARM DomU,
KVM and XEN x86 seems use emulated RTC in qemu. Thinking of paravirtual RTC, and dom0
control the expire time for alarm.

Thanks,
Peng.

> 
> Cheers,
> 
> --
> Julien Grall
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Re: Does XEN ARM support RTC in domu?

[Julien Grall]

On 11/1/18 3:37 AM, Peng Fan wrote:
> Hi Julien,

Hi Peng,


>> -----Original Message-----
>> From: Julien Grall [mailto:julien.grall@arm.com]
>> Sent: 2018年11月1日 2:52
>> To: Peng Fan <peng.fan@nxp.com>; xen-devel@lists.xenproject.org; Stefano
>> Stabellini <sstabellini@kernel.org>
>> Subject: Re: Does XEN ARM support RTC in domu?
>>
>>
>>
>> On 10/31/18 1:57 PM, Peng Fan wrote:
>>> Hi All,
>>
>> Hi,
>>
>>>
>>> Just have a question, does XEN ARM support RTC in domu? To support Android
>> in DomU, RTC is needed for alarm, but I did not find information about RTC on
>> xen for domu. So this need a new RTC paravirtualization driver? Any suggestions?
>>
>> By RTC, do you mean Real-Time Clock? Something like PL031? Or do you have
>> something else in mind?
> 
> Yes, Real Time Clock like PL031 in DomU. I do not have a good idea support RTC in ARM DomU,
> KVM and XEN x86 seems use emulated RTC in qemu. Thinking of paravirtual RTC, and dom0
> control the expire time for alarm.

The PL031 is quite small (based on the QEMU version). So I think it 
would be fine to provide an emulation in the hypervisor.

Cheers,

-- 
Julien Grall

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Re: Does XEN ARM support RTC in domu?

[Peng Fan]

Hi Julien,

> >>
> >>>
> >>> Just have a question, does XEN ARM support RTC in domu? To support
> >>> Android
> >> in DomU, RTC is needed for alarm, but I did not find information
> >> about RTC on xen for domu. So this need a new RTC paravirtualization driver?
> Any suggestions?
> >>
> >> By RTC, do you mean Real-Time Clock? Something like PL031? Or do you
> >> have something else in mind?
> >
> > Yes, Real Time Clock like PL031 in DomU. I do not have a good idea
> > support RTC in ARM DomU, KVM and XEN x86 seems use emulated RTC in
> > qemu. Thinking of paravirtual RTC, and dom0 control the expire time for
> alarm.
> 
> The PL031 is quite small (based on the QEMU version). So I think it would be fine
> to provide an emulation in the hypervisor.

Ok. Just like the hvm x86, implement emulate PL031 inside XEN. I'll give a try.

Thanks,
Peng.

> 
> Cheers,
> 
> --
> Julien Grall
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Re: Does XEN ARM support RTC in domu?

[Peng Fan]

Hi Julien,

> -----Original Message-----
> From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On Behalf Of
> Peng Fan
> Sent: 2018年11月5日 10:11
> To: Julien Grall <julien.grall@arm.com>; xen-devel@lists.xenproject.org;
> Stefano Stabellini <sstabellini@kernel.org>
> Subject: Re: [Xen-devel] Does XEN ARM support RTC in domu?
> 
> Hi Julien,
> 
> > >>
> > >>>
> > >>> Just have a question, does XEN ARM support RTC in domu? To support
> > >>> Android
> > >> in DomU, RTC is needed for alarm, but I did not find information
> > >> about RTC on xen for domu. So this need a new RTC paravirtualization
> driver?
> > Any suggestions?
> > >>
> > >> By RTC, do you mean Real-Time Clock? Something like PL031? Or do
> > >> you have something else in mind?
> > >
> > > Yes, Real Time Clock like PL031 in DomU. I do not have a good idea
> > > support RTC in ARM DomU, KVM and XEN x86 seems use emulated RTC in
> > > qemu. Thinking of paravirtual RTC, and dom0 control the expire time
> > > for
> > alarm.
> >
> > The PL031 is quite small (based on the QEMU version). So I think it
> > would be fine to provide an emulation in the hypervisor.
> 
> Ok. Just like the hvm x86, implement emulate PL031 inside XEN. I'll give a try.

Just a follow up question, emulating PL031 in xen, do you have idea how to inject virtual interrupt to domu?
The interrupt should be only cpu interface interrupt, I think.

Thanks,
Peng.
> 
> Thanks,
> Peng.
> 
> >
> > Cheers,
> >
> > --
> > Julien Grall
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Re: Does XEN ARM support RTC in domu?

[Stefano Stabellini]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1618 bytes --]

On Tue, 6 Nov 2018, Peng Fan wrote:
> Hi Julien,
> 
> > -----Original Message-----
> > From: Xen-devel [mailto:xen-devel-bounces@lists.xenproject.org] On Behalf Of
> > Peng Fan
> > Sent: 2018年11月5日 10:11
> > To: Julien Grall <julien.grall@arm.com>; xen-devel@lists.xenproject.org;
> > Stefano Stabellini <sstabellini@kernel.org>
> > Subject: Re: [Xen-devel] Does XEN ARM support RTC in domu?
> > 
> > Hi Julien,
> > 
> > > >>
> > > >>>
> > > >>> Just have a question, does XEN ARM support RTC in domu? To support
> > > >>> Android
> > > >> in DomU, RTC is needed for alarm, but I did not find information
> > > >> about RTC on xen for domu. So this need a new RTC paravirtualization
> > driver?
> > > Any suggestions?
> > > >>
> > > >> By RTC, do you mean Real-Time Clock? Something like PL031? Or do
> > > >> you have something else in mind?
> > > >
> > > > Yes, Real Time Clock like PL031 in DomU. I do not have a good idea
> > > > support RTC in ARM DomU, KVM and XEN x86 seems use emulated RTC in
> > > > qemu. Thinking of paravirtual RTC, and dom0 control the expire time
> > > > for
> > > alarm.
> > >
> > > The PL031 is quite small (based on the QEMU version). So I think it
> > > would be fine to provide an emulation in the hypervisor.
> > 
> > Ok. Just like the hvm x86, implement emulate PL031 inside XEN. I'll give a try.
> 
> Just a follow up question, emulating PL031 in xen, do you have idea how to inject virtual interrupt to domu?
> The interrupt should be only cpu interface interrupt, I think.

Have a loop at the existing virtual timer: xen/arch/arm/vtimer.c
It should give you a decent idea.

[-- Attachment #2: Type: text/plain, Size: 157 bytes --]

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