在2025年5月19日周一 上午9:55，Bibo Mao写道：
[...]
>> It's actually different machine as kernel irqchip is never on par with
>> usermode
>> emulation. This approach is taken by i386 (TYPE_KVM_IOAPIC vs TYPE_IOAPIC),
>> Arm (TYPE_KVM_ARM_ITS vs TYPE_ARM_GICV3_ITS), PowerPC (TYPE_KVM_OPENPIC vs
>> TYPE_OPENPIC) and I see no reason that LoongArch should not follow.
> So what is the advantage and disadvantage from yourself understanding here?
I think I made myself pretty clear in previous replies, in case you missed
that.
The advantage is clean design, clean interface, clean vmstates (user space
emulation
tends to have more states vs in-kernel irqchip), proper signalling to user that
migration between user-space/in-kernel irqchip is not feasible, perhaps some
performance
advantage on reducing number of user space IOCSR ranges, reducing attack surface
exposed by userspace emulation, reducing the chance of hypervisor error being
covered
up by userspace fallback....
I don't think there is any disadvantage. I don't really buy the "different
machine"
justification you made. Paravirt solution tends to have its own behaviour and I
don't
think it's a bad thing to expose it to users.
Thanks
--
- Jiaxun
