Re: kernel device reset support

Dong, Eddie
2007-10-16T08:44:26Z

Avi Kivity wrote:
> Dong, Eddie wrote:
>>> N+1, for me is that synchronous device emulation (like pio and mmio)
>>> happens in in the vcpu thread and asynchronous device emulation
>>> (handling signals in qemu, performing dma, and injecting interrupts)
>>> happens in the device thread. This minimizes context switching and
>>> heavyweight exits.
>>>
>>>
>> If this is true, then the N+1 thread won't be able to execute
>> qemu_system_reset which is in VCPU contents,
>
> I don't understand. It can certainly access any qemu object (after
> taking qemu_mutex), and it can call any kvm vm ioctl.

It can in theory, but do we have the real usage for
qemu_system_reset which is the only caller of
KERNEL RESET.

>
>
>> nor can asyn I/O call back APIs.
>>
>
> Do you mean signal handlers? Sure, but we wait for socket I/O in
> select() and even dequeue signals synchronously.
>
>
Qemu_system_reset is called only when a VCPU thread is doing.

Anyway, wanna to see your whole proposal.
thx,eddie