On Mon, Aug 24 2020 at 08:21, Jürgen Groß wrote: > On 21.08.20 02:24, Thomas Gleixner wrote: > > Looking into https://www.kernel.org/doc/Documentation/IRQ-domain.txt (is > this still valid?) It's halfways correct. Emphasis on halfways. > I believe Xen should be able to use the "No Map" approach, as Xen only > ever uses software IRQs (at least those are the only ones visible to > any driver). The (virtualized) hardware interrupts are Xen events > after all. > > So maybe morphing Xen into supporting irqdomains in a sane way isn't > that complicated. Maybe I'm missing the main complexities, though. The wrapper domain I did is pretty much that, but with the extra functionality required by hierarchical irq domains. So, yes it's functionally correct, but it's only utilizing the alloc/free interface and not any of the other mechanisms provided by irqdomains. The latter should make the overall code simpler but that obviously needs some thought. Thanks, tglx
