Re: Renesas R-Car Gen3 SoCs earlyprintk support.

[Julien Grall <julien.grall@arm.com>]

Hi Andrii,

On 06/07/17 13:24, Andrii Anisov wrote:
> On 06.07.17 14:43, Julien Grall wrote:
>> Well, I would expect no changes in either in the BSP, kernel,
>> device-tree when you run with Xen.
> Even without adding XEN specific chosen node? Or you do not count it as
> a devtree change?

I don't count the chosen node. This could be done via the u-boot command 
line, so no need to load a separate DT.

>
>>>> The wiki page gives the false impression that Xen upstream is fully
>>>> supported on Renesas, whilst from what you said this is not true and
>>>> change are required in the BSP.
>>> I would say in different words: XEN upstream is fully supported on
>>> Renesas, but due to XEN functionality gaps the BSP should be adjusted
>>> appropriately.
>>
>> You can't say in the same sentence, the board is fully supported and
>> there are missing functionality that requires change in the BSP. They
>> are incompatible.
>>
>> I agree that we are able to boot Xen on Renesas (not sure to which
>> extend without modification). But you can't claim it is fully
>> supported until all those gaps are fixed.
> Well...
> Do you say that calls to ARM TEE from XEN domains works for all
> supported boards? And smc trapping is somehow Renesas specific?

I am not aware of any board we currently support requiring to issue SMC 
calls.

We used to have one in the past, but this has been fixed in the BSP to 
avoid issuing SMC when it is not allowed.

> Or you state that TEE is never provided as a part of BSP for supported
> boards? So nobody mention the gap?

You are the first person looking actively at TEE with Xen upstream. I 
personally don't have any board that is using TEE.

Are you saying TEE will not be detected via the Device Tree and the BSP 
will always assume it is present?

> Maybe you claim BSP of all supported boards goes out of bootloader in
> Hypervisor mode/EL2? So no changes to FW/bootloader should be ever done
> for supported boards?

If the bootloader does not leave you in EL2, then it is a bug in the 
bootloader that should be fixed in the official BSP. Not in a separate 
repository just for Xen.

My point is we should work with Renesas to get the official BSP to 
support Xen rather than forking the BSP and carry all the changes.

This is more sustainable and less overhead for everyone in the future.

Cheers,

-- 
Julien Grall

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