[PATCH v12 05/13] blk-mq: add blk_mq_{online|possible}_queue_affinity

[Daniel Wagner]

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.