Re: [Xen-devel] Compatible string for psci node: v1.0?

[Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>]

Hi Julien,

Thanks, it looks like the issue was with the way I verified this - cat on /sys/firmware/devicetree/base/psci/compatible from dom0's console returns only the first compatible string set by Xen no matter what.

I have verified by debugging that linux finds the right compatible string in psci_dt_init().

Thanks,

Mirela

On Thu, Feb 1, 2018 at 8:12 PM, Julien Grall <julien.grall@xxxxxxx> wrote:

On 01/02/18 19:00, Mirela Simonovic wrote:

Hi,

Hi Mirela,

I'm working on switching to PSCI v1.0 in Xen (needed to support suspend  > to RAM).

I am about to send a series to add support for PSCI 1.1 (I need it for the spectre mitigation). I can send you a temporary branch if you want to see whether I missed anything.

In addition to updates in PSCI implementation, we assumed that compatible property in psci device tree node should be extended with "arm,psci-1.0" (not a must since this doesn't affect Dom0's functionality today, but I would add it if possible).

Could you please let me know how to add "arm,psci-1.0" to compatible property?

I assumed that in domain_build.c in make_psci_node() function I need to add "arm,psci-1.0""\0" at the beginning of 'compat' string (although I don't understand the "\0"). That doesn't seem to work. Only "arm,psci-1.0" ends up in compatible property and we need strings for older versions as well.
I also noticed that even "arm,psci" doesn't appear to be added into the compatible property (without any code modifications from my side). I checked what is generated by debugging and by 'cat' on /sys/firmware/devicetree/base/psci/compatible from Dom0's console.

>From the DT specification, each compatible string should be separated by '\0'. Doing a hexdump -C in the hardware domain I can see that both arm,psci and arm,psci-0.2 are present on latest Xen. So I am not sure why it would not be present on your side.

BTW, if you use printk, only the first compatible will be printed (printk stop at the '\0').

Cheers,

--
Julien Grall

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