On Thu, 11 Sep 2025 11:32:56 +0200, Johannes Berg wrote: > On Sun, 2025-08-10 at 13:51 +0800, Tiwei Bie wrote: > > From: Tiwei Bie <tiwei....@antgroup.com> > > > > Add initial symmetric multi-processing (SMP) support to UML. With > > this support enabled, users can tell UML to start multiple virtual > > processors, each represented as a separate host thread. > > > > In UML, kthreads and normal threads (when running in kernel mode) > > can be scheduled and executed simultaneously on different virtual > > processors. However, the userspace code of normal threads still > > runs within their respective single-threaded stubs. > > > > That is, SMP support is currently available both within the kernel > > and across different processes, but still remains limited within > > threads of the same process in userspace. > > Another thing that isn't covered is anything relating to interrupt > affinity, I guess? Is that automatically not working, or will it look > like you can change things but that not do anything? > > I don't think it's important now (though eventually I would actually > like to have it for our simulations), but was just thinking about it.
Currently, our irq_chips haven't implemented the irq_set_affinity method, so setting IRQ affinity is not supported at the moment, e.g., attempting to set affinity through /proc/irq/IRQ#/smp_affinity will fail with EPERM. And yeah, we should support it eventually. :) Regards, Tiwei
