>Ingo Molnar wrote: >> we should move all the PICs into KVM proper - and that includes the >> i8259A PIC too. Qemu-space drivers are then wired to pins on these PICs, >> but nothing in Qemu does vector generation or vector prioritization - >> that task is purely up to KVM. There are mixed i8259A+lapic models >> possible too and the simplest model is to have all vector handling in >> KVM. >> >> any 'cut' of the interface to allow both qemu and KVM generate vectors >> is unnecessary (and harmful) complexity. The interface cut should be at >> the 'pin' level, with Qemu raising a signal on a pin and lowering a >> signal on a pin, but otherwise not dealing with IRQ routing and IRQ >> vectors. >> > >Following is my view of the possible cuts: > >- everything in userspace: worst performance, but needed for comaptibility > >- tpr in kernel: minimal effort, bad badly defined interface > >- lapic in kernel: well defined (all on-chip stuff in kernel, off-chip >in userspace), fixes main Windows problems, interrupts still need >userspace. Interface is the processor's LINT pins and APIC bus. > >- *pic in kernel: most effort, easiest irq synchronization. Interface >is pic/ioapic pin level, plus a topology description that userspace uses >to tell the hardware how the pins are connected (logically required, but >practically not).
I vote for the *pic in kernel: - Clean 'cut', kills all the future arguments against moving things around - Easier to define a stable interface - Easy support for PV drivers - Easy hw assist acceleration - Provides the best performance ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
