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Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259 |
Date: |
Mon, 05 Dec 2011 14:55:51 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-12-05 14:36, Avi Kivity wrote:
> On 12/05/2011 03:29 PM, Jan Kiszka wrote:
>> On 2011-12-05 14:14, Avi Kivity wrote:
>>> On 12/05/2011 02:47 PM, Jan Kiszka wrote:
>>>>>
>>>>> (the memory API added unstable names, hopefully the QOM can take over
>>>>> the stable ones and we'll have a good way to denote the unstable ones).
>>>>>
>>>>
>>>> OK, maybe - or likely - we should make those device models have the same
>>>> names in QOM once instantiated. But I'm still convinced they should
>>>> remain separated models in contrast to a single model with a property.
>>>
>>> What do you mean by separate models? You share all the code you can,
>>> and don't share the code you can't. To me, single model == single name.
>>
>> But different configuration.
>
> Right, just like IDE with different backends.
Except that there is a comparably large infrastructure to manage those
backends.
>
>>>
>>>> The kvm ioapic, e.g., requires an additional property (gsi_base) that is
>>>> meaningless for user space devices. And its interrupts have to be
>>>> wired&configured differently at board model level. So, from the QEMU
>>>> POV, it is a very different device. Just the guest does not notice.
>>>
>>> It's like qcow2 and raw/native IO are wire differently, or virtio-net
>>> and vhost-net. But it's the same IDE device or virtio NIC.
>>
>> That would mean introducing a backend/frontend concept for irqchips.
>
> We could do it, have one ioapic model with ioapic_ops->eoi_broadcast().
> Most of the interfaces already dispatch dynamically (qdev gpio/irq) so
> there wouldn't be much more there.
The problem is configuration. Just by setting ioapic.backend=xxx, we
cannot pass down parameters that are backend-specific. We could ignore
this issue and make all specific parameters visible via the frontend.
Would be slightly ugly.
>
> To me, how it's actually implemented is not important. What is
> important is that save/restore, the monitor, and the guest don't notice
> any changes.
I widely agree, except that differentiation (or backend awareness) has
to be preserved in the monitor.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, (continued)
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Avi Kivity, 2011/12/04
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Blue Swirl, 2011/12/04
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Jan Kiszka, 2011/12/04
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Avi Kivity, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Jan Kiszka, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Avi Kivity, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Jan Kiszka, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Avi Kivity, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Jan Kiszka, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259, Avi Kivity, 2011/12/05
- Re: [Qemu-devel] [RFC][PATCH 14/16] kvm: x86: Add user space part for in-kernel i8259,
Jan Kiszka <=
[Qemu-devel] [RFC][PATCH 12/16] kvm: x86: Establish IRQ0 override control, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 09/16] ioapic: Factor out core for KVM reuse, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 06/16] i8259: Factor out core for KVM reuse, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 13/16] kvm: x86: Add user space part for in-kernel APIC, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 15/16] kvm: x86: Add user space part for in-kernel IOAPIC, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 07/16] ioapic: Convert to memory API, Jan Kiszka, 2011/12/03
[Qemu-devel] [RFC][PATCH 04/16] apic: Factor out core for KVM reuse, Jan Kiszka, 2011/12/03