Jailhouse on iMX8M

[Anders Törnqvist]

I noticed that there are development ongoing for a iMX8M based board. Great!

When reading in the reference manual for iMX8M it does not have information about that the chip has virtualization extensions.

The web information about another chip - iMX8 - clearly talks about virtualization extentions.

The existing Jailhouse development for the iMX8M must be a proof of some support for virtualization.

Right?

Can anyone please clarify what the iMX8M has that makes it work with Jailhouse? And what about virtualization makes it different from the iMX8?

/Anders

[Peng Fan]

Hi Anders,

On Mon, Mar 12, 2018 at 04:52:35PM +0100, Anders T??rnqvist wrote:
>I noticed that there are development ongoing for a iMX8M based board. Great!
>
>When reading in the reference manual for iMX8M it does not have information about that the chip has virtualization extensions.
>The web information about another chip - iMX8 - clearly talks about virtualization extentions.
>
>The existing Jailhouse development for the iMX8M must be a proof of some support for virtualization.
>Right?

The i.MX8M supports ARM virtualization extension.

>
>Can anyone please clarify what the iMX8M has that makes it work with Jailhouse? And what about virtualization makes it different from the iMX8?

i.MX8M does not have SMMU.

Regards,
Peng.
>
>/Anders
>
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[Lokesh Vutla]

Hi Peng,
Sorry to bring up an old thread.

On 13/03/18 9:43 AM, Peng Fan wrote:
> Hi Anders,
> On Mon, Mar 12, 2018 at 04:52:35PM +0100, Anders T??rnqvist wrote:
>> I noticed that there are development ongoing for a iMX8M based board. Great!
>>
>> When reading in the reference manual for iMX8M it does not have information about that the chip has virtualization extensions.
>> The web information about another chip - iMX8 - clearly talks about virtualization extentions.
>>
>> The existing Jailhouse development for the iMX8M must be a proof of some support for virtualization.
>> Right?
>
> The i.MX8M supports ARM virtualization extension.

I am bit exited to see a doc[1] saying that iMX8Qm doesn't need a SW hypervisor
for running two OSs on the same SoC. Out of curiosity, was wondering how does
the IRQ routing happens without hypervisor? Also I am interested to see more
details on this problem. Are there any public docs that I take a look?

[1] https://community.nxp.com/docs/DOC-341849

Thanks and regards,
Lokesh

[Peng Fan]

Hi Lokesh

It is i.MX8QM, not i.MX8M :)

It was developed by other team, I do not have much info.
There is only one GIC controller, so need to config GIC distribute to make sure
SPI are routed to cores correctly, and linux gic code also needs to be modified.

Regards,
Peng.

>
> [1]
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcom
> munity.nxp.com%2Fdocs%2FDOC-341849&data=02%7C01%7Cpeng.fan
> %40nxp.com%7C18283eeda33f483ca52208d6756c8c25%7C686ea1d3bc2b4c
> 6fa92cd99c5c301635%7C0%7C0%7C636825506399672229&sdata=Li8l
> 2qeIvkiJU2Wd7quU8cWM9JGV0imr7PSxezP4WYE%3D&reserved=0

>
> Thanks and regards,
> Lokesh
>
> >
> >>
> >> Can anyone please clarify what the iMX8M has that makes it work with
> Jailhouse? And what about virtualization makes it different from the iMX8?
> >
> > i.MX8M does not have SMMU.
> >
> > Regards,
> > Peng.
> >>
> >> /Anders
> >>
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> c5c301635%7C0%7C0%7C636825506399682233&sdata=440CxtYt3175z
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> >
>
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[Lokesh Vutla]

If linux driver is used for configuring gic, then one VM can potentially screw
other VM interrupts no? But anyways it is interesting to see how all the these
problems are solved without hypervisor :)

Thanks and regards,
Lokesh

[Jan Kiszka]

I suppose it boils down to the questions who is in charge of configuring the
shared resources and who can control the access to it - or it is just standard
collaborative AMP, something everyone did before the arrival of virtualization.

Jan

--
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

[Peng Fan]

To run without hypervisor, first need to disable coherency between the OSes,
on i.MX8QM, it is cluster coherency disabled.
The major issue is GIC. About gic, OS only need to touch gic cpu interface which
is per cpu, no need touch gic distributor. Anyway this has no chance to be accepted by Linux Kernel.

Regards,
Peng.

[andrew.no...@gmail.com]

Peng,

Is there open source available somewhere that shows the changes to Linux required to get Jailhouse running on an iMX8M?

Regards,

Andrew