chcpu(8): document limitations of -g

Document that chcpu -g is not supported on IBM z/VM because the detach cpu
would CLEAR the running zVM guest memory.

References:
https://www.ibm.com/docs/en/linux-on-z?topic=mc-changing-state-1
https://www.ibm.com/docs/en/zvm/7.3?topic=commands-detach-cpu

Reported-by: Heikki Ylipiessa <heikki.ylipiessa@suse.com>
Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>

diff --git a/sys-utils/chcpu.8.adoc b/sys-utils/chcpu.8.adoc
index c5797dfb372dce09c3000264b3ad8080039d0703..80dfc5f202542190fca786f6acfed291d352145f 100644 (file)
--- a/sys-utils/chcpu.8.adoc
+++ b/sys-utils/chcpu.8.adoc
@@ -37,6 +37,8 @@ Enable the specified CPUs. Enabling a CPU means that the kernel sets it online.
 
 *-g*, *--deconfigure* _cpu-list_::
 Deconfigure the specified CPUs. Deconfiguring a CPU means that the hypervisor removes the CPU from the virtual hardware on which the Linux instance runs and returns it to the CPU pool. A CPU must be offline, see *-d*, before it can be deconfigured.
++
+*chcpu -g* is not supported on IBM z/VM, CPUs are always in a configured.
 
 *-p*, *--dispatch* _mode_::
 Set the CPU dispatching _mode_ (polarization). This option has an effect only if your hardware architecture and hypervisor support CPU polarization. Available _modes_ are: