Re: [PATCH v4] powerpc/pseries: read the lpar name from the firmware

On 1/5/22 3:19 PM, Nathan Lynch wrote:

Laurent Dufour [off-list ref] writes:

quoted

On 07/12/2021, 18:11:09, Laurent Dufour wrote:

quoted

The LPAR name may be changed after the LPAR has been started in the HMC.
In that case lparstat command is not reporting the updated value because it
reads it from the device tree which is read at boot time.

However this value could be read from RTAS.

Adding this value in the /proc/powerpc/lparcfg output allows to read the
updated value.

Do you consider taking that patch soon?

This version prints an error on non-PowerVM guests the first time
lparcfg is read.

I assume because QEMU doesn't implement the LPAR_NAME token for get_sysparm.

And I still contend that having this function fall back to reporting the
partition name in the DT would provide a beneficial consistency in the
user-facing API, allowing programs to avoid hypervisor-specific branches
in their code. 

Agreed, if the get_sysparm fails just report the lpar-name from the device tree.

I don't understand the resistance I've encountered here.

The fallback I'm suggesting (a root node property lookup) is certainly
not more complex than the RTAS call sequence you've already implemented.

Is there benefit of adding a partition_name field/value pair to lparcfg? The
lparstat utility can just as easily make the get_sysparm call via librtas.
Further, rtas_filters allows this particular RTAS call from userspace.

-Tyrel