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

On 06/01/2022, 02:17:21, Tyrel Datwyler wrote:

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

quoted

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.

quoted

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.

My aim is to not do in the kernel what can be easily done in user space but
avoiding user space program hypervisor-specific branches is a good point.

Note that if the RTAS call has been available to unprivileged user, all
that stuff would have been made in user space, so hypervisor-specific...

Anyway, I'll work on a new version fetching the DT value in the case the
RTAS call is failing.

Thanks,
Laurent.