On Mon, Apr 27, 2026 at 05:34:16PM +0200, Sebastian Andrzej Siewior wrote: > Which driver uses cpu_possible_mask? This mask is assigned at boot time > once the kernel figured how many CPUs are possible based on ACPI or > whatever the system uses. This mask does not change. > > I only see drivers/scsi/lpfc/lpfc_init.c using it. Looking at > cpu_possible_mask might not be the right thing. It is usually the same > thing as "online" except on system where ACPI thinks that something > could be added via hotplug _or_ if the admin shuts down a CPU via > cpuhotplug _or_ boots with less (there a command line option for > that).
These HBAs are used on PowerPC which supports lpar (CPUs can be added during runtime) I am told it's properly the only driver which is caring about this type configuration, thus a bit of an odd ball. > In case cpu_possible_mask != cpu_online_mask the intention is to > allocate memory and setup irqs for the offline CPUs? I can't answer this. The lpfc driver has several strategies implemented how it spreads its resources.
