On Wed, Mar 28, 2012 at 01:36:15PM +0200, Jan Kiszka wrote: > On 2012-03-28 13:31, Michael S. Tsirkin wrote: > >>>>> Also, how would this support irqfd in the future? Will we have to > >>>>> rip it all out and replace with per-device tracking that we > >>>>> have today? > >>>> > >>>> Irqfd and kvm device assignment will require additional interfaces (of > >>>> the kvm core in QEMU) via which you will be able to request stable > >>>> routes from such sources to specified MSIs. That will be widely > >>>> orthogonal to what is done in these patches here. > >>> > >>> Yes but not exactly as they will conflict for resources, right? > >>> How do you plan to solve this? > >> > >> As done in my original series: If a static route requires a pseudo GSI > >> and there are none free, we simply flush the dynamic MSI routes. > > > > Right. So static routes take precedence. This means that in effect > > we will have two APIs in qemu: for fast MSIs and for slow ones, > > the advantage of the slow APIs being that they are easier to use, > > right? > > We will have two APIs depending on the source of the MSI. Special > sources are the exception while emulated ones are the majority. And for > the latter we should try very hard to keep things simple and clean. > > Jan I assume this means yes :) So how about we replace the hash table with a single GSI reserved for this purpose, and use that for each interrupt? This will work fine for slow paths such as hotplug controller, yes it will be slow but *predictably* slow. Fast path will use static GSIs like qemu-kvm does. > -- > Siemens AG, Corporate Technology, CT T DE IT 1 > Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
