Re: [Qemu-devel] [PATCH for-2.8 00/18] pc: q35: x2APIC support in kvm_apic mode

[Igor Mammedov]

On Mon, 8 Aug 2016 15:41:23 +0800
Chao Gao <address@hidden> 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?
I don't think we ever looked at "kernel-irqchip=split" only in kernel variant's
been targeted so far.
Radim probably knows better whether it should work or not.

Have you tried with smaller amount of CPUs but with APIC IDs above 254,
like in test below?

[...]

> >Tested with following CLI:
> > QEMU -M q35 -enable-kvm -smp 1,sockets=9,cores=32,threads=1,maxcpus=288 \
> >      -device qemu64-x86_64-cpu,socket-id=8,core-id=30,thread-id=0       \
> >      -bios x2apic_bios.bin