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Re: [Qemu-devel] [PATCH v2 1/3] q35: set split kernel irqchip as default
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/3] q35: set split kernel irqchip as default |
Date: |
Fri, 3 May 2019 15:42:06 -0300 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Mon, Apr 29, 2019 at 09:22:12AM -0600, Alex Williamson wrote:
[...]
> > > What's a good 4.0.1 strategy to resolve this? Re-instate KVM irqchip
> > > as the Q35 default? I can't see that simply switching to current QEMU
> > > handling is a viable option for performance? What about 4.1? We could
> > > certainly improve EOI support in QEMU, there's essentially no support
> > > currently, but it seems like an uphill battle for an iothread based
> > > userspace ioapic to ever compare to KVM handling? Thanks,
> >
> > irqchip=split and irqchip=kernel aren't guest ABI compatible, are
> > they? That would make it impossible to fix this in pc-q35-4.0
> > for a 4.0.1 update.
>
> I suppose it would require a pc-q35-4.0.1 machine type :-\ Thanks,
I wonder if it's possible to untangle this and make the irqchip
option stop affecting guest ABI on 4.1+ machine-types? This way
QEMU could choose smarter defaults in the future without the
compatibility code hassle.
--
Eduardo
- Re: [Qemu-devel] [PATCH v2 1/3] q35: set split kernel irqchip as default,
Eduardo Habkost <=