Re: Renesas R-Car Gen3 SoCs earlyprintk support.

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

Hi Andrii,

On 06/07/17 12:31, Andrii Anisov wrote:
>
> On 05.07.17 20:18, Julien Grall wrote:
>> I prefer to say: "This is not supported today because of XXX. With the
>> following patches, it is possible to boot.". Rather than "This is
>> supported if you download from this github, I don't give Xen version
>> and don't even mention the patches on top...".
> Actually statements "Xen is fully supported" and "changes are required
> in the BSP" do not contradict each other, if we treat those changes
> (disabling OP-TEE) as a matter of BSP configuration (which they are). Do
> you agree?

Well, I would expect no changes in either in the BSP, kernel, 
device-tree when you run with Xen.

For all the platform currently supported, we can boot Xen with the 
device-tree provided by the firmware or from Linux upstream. The Linux 
kernel is not modified but recompiled with XEN options enabled.

Xen should take care of the missing mappings and/or disabling device not 
supported.

So I don't see how the Renesas board should be different here. If you 
need to modify the device-tree or Linux. Then there is missing pieces in 
Xen or the BSP is not doing the right thing (i.e auto-detect support).

>
>> 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.

Anyway, we should at least list the gaps on the wiki page for helping 
potential users.

Cheers,

-- 
Julien Grall

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