Date: Fri, 3 May 2019 17:23:25 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
Message-ID: <20190503202325.GA27890@habkost.net>
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Subject: Re: [Qemu-devel] [PATCH v2 1/3] q35: set split kernel irqchip as
 default
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Igor Mammedov <imammedo@redhat.com>, qemu-devel@nongnu.org, Peter Xu <peterx@redhat.com>

On Fri, May 03, 2019 at 04:00:33PM -0400, Michael S. Tsirkin wrote:
> On Mon, Apr 29, 2019 at 11:55:56AM -0300, Eduardo Habkost wrote:
> > irqchip=split and irqchip=kernel aren't guest ABI compatible, are
> > they?
> 
> Can you remind me why they aren't?

We have the code introduced by patch 3/3 from this series, but I
don't know if it's the only difference:

hw/i386/x86-iommu.c=static void x86_iommu_realize(DeviceState *dev, Error **errp)
[...]
hw/i386/x86-iommu.c:    bool irq_all_kernel = kvm_irqchip_in_kernel() && !kvm_irqchip_is_split();
[...]
hw/i386/x86-iommu.c-    /* If the user didn't specify IR, choose a default value for it */
hw/i386/x86-iommu.c-    if (x86_iommu->intr_supported == ON_OFF_AUTO_AUTO) {
hw/i386/x86-iommu.c-        x86_iommu->intr_supported = irq_all_kernel ?
hw/i386/x86-iommu.c-            ON_OFF_AUTO_OFF : ON_OFF_AUTO_ON;
hw/i386/x86-iommu.c-    }

-- 
Eduardo