Hi Jan,
On 18/09/2025 15:51, Jan Beulich wrote:
On 18.09.2025 15:35, Julien Grall wrote:
On 18/09/2025 13:16, Mykyta Poturai wrote:
+static long cpu_hotplug_sysctl(struct xen_sysctl_cpu_hotplug *hotplug)
+{
+ bool up;
+
+ switch (hotplug->op) {
+ case XEN_SYSCTL_CPU_HOTPLUG_ONLINE:
+ if ( hotplug->cpu == 0 )
I can't find a similar check on x86. Do you have any pointer?
When CPU 0 cannot be brought down (see cpu_down()), tryin to bring it up
is kind of pointless, and hence can perhaps be short circuited like this?
Thanks for the clarification, I missed the check in cpu_down(). That
said, I don't see any value to short circuit it. In fact, I see this as
more a risk because if we ever decide to allow CPU 0 to be offlined,
then it would be more difficult to find places where we short circuit it.
So I would rather prefer if we remove the checks.
Cheers,
--
Julien Grall
