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

[Blue Swirl]

On Sun, Dec 4, 2011 at 16:35, Avi Kivity <address@hidden> wrote:
> On 12/04/2011 05:19 PM, Jan Kiszka wrote:
>> >
>> > In the sense that kernel-apic is just an accelerated apic.  From the
>> > guest point of view, there's no difference, and that should be reflected
>> > in the device model.
>>
>> That was my goal as well: The guest should not notice the difference,
>> but the admin on the host side should still be able to tell both
>> internally fairly different models apart.
>
> This should be some attribute, not the name.
>
>> Plus the code should be
>> clearly split where there are differences and explicitly shared where
>> there aren't.
>
> That's a good goal, yes.

I'd prefer an unified device built from a single source file if
possible. This conflicts with the build-once model though.

>>
>> >
>> > If I'm reading an apic register, either from the guest or via a monitor
>> > debug interface, I shouldn't care whether it's accelerated or not.  The
>> > guest part already holds, of course.
>>
>> Specifically for the debug scenario, I'd prefer the clear
>> differentiation by name as there can always remain subtle differences in
>> the implementation of kernel vs. user space. Someone debugging the guest
>> and/or qemu/kvm should remain aware of this.
>
> Aware, yes, but the name change is too drastic.

It should be also possible to migrate from non-KVM device to KVM
version, different names would prevent that for ever.