On Mon, Aug 08, 2016 at 04:57:14PM +0800, Peter Xu wrote: >On Mon, Aug 08, 2016 at 03:41:23PM +0800, Chao Gao wrote: >> HI, everyone. >> >> We have done some tests after merging this patch set into the lastest qemu >> master. In kvm aspect, we use the lastest kvm linux-next branch. Here are >> some problems we have met. >> >> 1. We can't boot up a 288 vcpus linux guest with CLI: >> qemu-system-x86_64 -boot c -m 4096 -sdl -monitor pty --enable-kvm \ >> -M kernel-irqchip=split -serial stdio -bios bios.bin -smp cpus=288 \ >> -hda vdisk.img -device intel-iommu,intremap=on -machine q35. >> The problem exists, even after we only assign 32 vcpus to the linux guest. >> Maybe the output "do_IRQ: 146.113 No irq handler for vector (irq -1)" is a >> clue. >> The output of qemu and kernel is in attachments. Do you have any idea >> about the problem and how to solve it? > >IIUC, we need to wait for Radim's QEMU patches to finally enable 288 >vcpus? > >Btw, could you please try adding this to the QEMU cmdline when testing >with 32 vcpus: > > -global ioapic.version=0x20 > >I see that you were running RHEL 7.2 guest with a default e1000. In >that case, we may need to boost ioapic version to 0x20.
It doesn't work. My host machine has 16 cpus. When I assign 4 or 8 vcpus to the guest or 255 vcpus but set "kernel-irqchip=off", the guest work well. Maybe when irqchip is in kernel, intremap can only handle situations that vcpus number is less than physical cpus'. Do you think it's right? Thanks, -Chao
