Re: [PATCH v3] powerpc/pseries: read the lpar name from the firmware

On 07/12/2021, 18:18:40, Laurent Dufour wrote:

On 07/12/2021, 18:07:50, Nathan Lynch wrote:

quoted

Laurent Dufour [off-list ref] writes:

quoted

On 07/12/2021, 15:32:39, Nathan Lynch wrote:

quoted

Is there a reasonable fallback for VMs where this parameter doesn't
exist? PowerVM partitions should always have it, but what do we want the
behavior to be on other hypervisors?

In that case, there is no value displayed in the /proc/powerpc/lparcfg and
the lparstat -i command will fall back to the device tree value. I can't
see any valid reason to report the value defined in the device tree
here.

Here's a valid reason :-)

lparstat isn't the only possible consumer of the interface, and the
'ibm,partition-name' property and the dynamic system parameter clearly
serve a common purpose. 'ibm,partition-name' is provided by qemu.

If the hypervisor is not providing this value, this is not the goal of this
interface to fetch it from the device tree.

Any consumer should be able to fall back on the device tree value, and
there is no added value to do such a trick in the kernel when it can be
done in the user space.

quoted

In any case, the function should not print an error when the return
value is -3 (parameter not supported).

That's a valid requirement.

I sent a v4 which is printing an error message even if the parameter is not
supported by the hypervisor.

This is unlikely and since this a call to pr_err_once(), it would be
printed only once, so not really annoying. I don't think a v5 is required
for such a minor message.