Re: [Xen-devel] [PATCH v2] xen/arm: Switch OMAP5 secondary cores into hyp mode

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

Hello Julien,

I put my two cents in:

On 18.07.19 13:09, Julien Grall wrote:
> On 7/17/19 10:55 PM, Denis Obrezkov wrote:
> > Hi,
> Hi,
>
> > > Well, Xen has been supported the omap5 for quite a while. So there are
> > > two possibilities regarding the current SMP code:
> > >     1) It is totally broken and therefore never worked on any omap5
> > > platform.
> > >     2) It works but with maybe modification in U-boot.
It works on Jacinto6 (dra7xx) with modifications in u-boot. As suggested in 
4557c2292854d047ba8e44a69e2d60d99533d155. I'd cite the message:

    As part of this change drop support for switching from secure mode to NS 
HYP as
    well as the early CPU kick. Xen now requires that it is launched in NS HYP
    mode and that firmware configure things such that secondary CPUs can be 
woken
    up by a primarly CPU in HYP mode. This may require fixes to bootloaders or 
the
    use of a boot wrapper.

I'm not sure what Chen upstreamed for OMAP5. Prior to 4557c2292 there is no 
mode switch code for omap5. Maybe, it was a switch in u-boot from the beginning.

If we are talking about beagleboard-x15 it has no OMAP5, but has Sitara AM5728 
SoC. Surprisingly, in am57xx-beagle-x15-common.dtsi, I see the following:
    
    compatible = "ti,am572x-beagle-x15", "ti,am5728", "ti,dra742", "ti,dra74", "ti,dra7";
I guess we also need another patch which adds "ti,am5728" as the platform 
supported by XEN.

> > > Looking at the mailing list archive and wiki, I believe 2) is closer to
> > > the current reality. So this raise the question whether your patch will
> > > break any existing setup.
I'd bet, the patch will not break support of any existing setup.
OMAP5 is discontinued long ago.
Jacinto6 (dra7xx) is from a conservative automotive world. Existing setups 
likely would not be updated. At least blindly. (I hope).
Sitara SoC's are not supported yet.

> if none is received then please go ahead resending a version with my analysis
From my point of view, the commit message should describe, that we are 
switching from the model suggested in 4557c2292854d047ba8e44a69e2d60d99533d155 
to a different one. With the appropriate reasoning, e.g. aligning to Linux 
kernel.

--
Sincerely,
Andrii Anisov.

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