Re: [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259

[Avi Kivity <avi@redhat.com>]

On 12/03/2011 01:17 PM, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
>
> Introduce the alternative 'kvm-i8259' device model that exploits KVM
> in-kernel acceleration.
>
> The PIIX3 initialization code is furthermore extended by KVM specific
> IRQ route setup. Moreover, GSI injection differs in KVM mode from the
> user space model. As we can dispatch ISA-range IRQs to both IOAPIC and
> PIC inside the kernel, we do not need to inject them separately. This is
> reflected by a KVM-specific GSI handler.
>
> +
> +qemu_irq *kvm_i8259_init(void)
> +{
> +    ISADevice *dev;
> +
> +    dev = isa_create("kvm-i8259");
>

Same issue.  Is this a different device, or an different implementation
of the same device?

We're forcing migration from 1.0 to 1.1 to disable in-kernel irqchip on
the target.  For qemu itself, that's no issue.  But for qemu-kvm, it
will result in loss of performance, or hacks to alias the two back together.

-- 
error compiling committee.c: too many arguments to function