Re: [Qemu-discuss] Longer time to detach device in q35

[Han Han]

On Sun, May 5, 2019 at 1:30 PM Han Han <address@hidden> wrote:

>
>
> On Sun, Apr 28, 2019 at 7:20 PM Maxim Levitsky <address@hidden>
> wrote:
>
>> I 'think' that this is due to the fact that Q35 uses the PCIe hotplug,
>> which was
>> done for real life PCIe hotplug which involves operator pressing a
>> button, and
>> then waiting for confirmation.
>>
>> The spec allows the operator to change his mind during 5 second timeout
>> (or
>> something similiar).
>>
>> Now what qemu does on hot unplug, is that it presses that button
>> logically, but
>> then the guest waits the 5 seconds before it acts upon it as written in
>> the
>> spec.
>>
>> I am a little confused about why it is designed as this way. Could you
> please show me the related pcie spec reference link or the qemu code of
> this function?
>
I have found that doc: https://wiki.qemu.org/images/f/f6/PCIvsPCIe.pdf
PCI Hot Plug --> Hot Remove Sequence:
Power LED blinks to indicate transition state. The operator is granted a 5
second
interval to cancel the request and the Hot Plug software validates the
request.

The 'pc' machine either uses acpi or older 'standard pci hotplug controller'
>> whic might lack this 'feature'
>>
>> I am adding Michael here, as I remember that he mentioned this once.
>>
>> Best regards,
>>         Maxim Levitsky
>>
>>
>
> --
> Best regards,
> -----------------------------------
> Han Han
> Quality Engineer
> Redhat.
>
> Email: address@hidden
> Phone: +861065339333
>


-- 
Best regards,
-----------------------------------
Han Han
Quality Engineer
Redhat.

Email: address@hidden
Phone: +861065339333