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Re: [Qemu-devel] [PATCH] pci: add standard bridge device
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [PATCH] pci: add standard bridge device |
Date: |
Wed, 02 Nov 2011 10:38:24 +0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 |
At 11/02/2011 10:15 AM, Isaku Yamahata Write:
> On Tue, Nov 01, 2011 at 04:49:08PM +0800, Wen Congyang wrote:
>> At 11/01/2011 04:44 PM, Michael S. Tsirkin Write:
>>> On Tue, Nov 01, 2011 at 09:27:25AM +0800, Wen Congyang wrote:
>>>> Hi, Michael S. Tsirkin
>>>>
>>>> At 09/26/2011 03:08 PM, Michael S. Tsirkin Write:
>>>>> On Mon, Sep 26, 2011 at 02:18:15PM +0800, Wen Congyang wrote:
>>>>>> Hi, Michael S. Tsirkin
>>>>>>
>>>>>> At 07/04/2011 05:43 PM, Michael S. Tsirkin Write:
>>>>>>> This adds support for a standard pci to pci bridge,
>>>>>>> enabling support for more than 32 PCI devices in the system.
>>>>>>> To use, specify the device id as a 'bus' option.
>>>>>>> Example:
>>>>>>> -device pci-bridge,id=bridge1 \
>>>>>>> -netdev user,id=u \
>>>>>>> -device ne2k_pci,id=net2,bus=bridge1,netdev=u
>>>>>>>
>>>>>>> TODO: device hotplug support.
>>>>>>
>>>>>> Do you have any plan to implement this?
>>>>>
>>>>> I think this will be needed before merging the bridge code.
>>>>
>>>> What will you plan to support?
>>>>
>>>> 1. all PCI-to-PCI bridge is not hotpluggable.
>>>> host bridge
>>>> |
>>>> ---------------------
>>>> | |
>>>> bridge bridge <= *not* hotpluggable
>>>> | |
>>>> ----------- ------------
>>>> | | | |
>>>> slot slot slot slot <= hotplug here
>>>>
>>>>
>>>> 2. PCI-to-PCI bridge is hotpluggable.
>>>> bridge
>>>> |
>>>> -------------------
>>>> | |
>>>> bridge on slot bridge on slot <= hot-plug here
>>>> | |
>>>> ------- -------
>>>> | | | |
>>>> slot slot slot slot <= hot-plug here
>>>>
>
> If P2P bridge hotplug is supported, pci bus numbering needs refinement
> for numbering bus sparsely.
>
>
>>>>>> I read the qemu's code, and find that qemu uses PIIX4_PM to support
>>>>>> pci device hot plugging on PCI bus 0. How to support it on the other
>>>>>> bus? Add PIIX4_PM to each PCI bus or implement a new power management?
>>>>>>
>>>>>> Thanks
>>>>>> Wen Congyang
>>>>>
>>>>> There are many valid options. One is shpc interface.
>>>>> I started looking into this but got preempted by other
>>>>> tasks. Hope to get back to this at some point.
>>>>
>>>> Some old OS does not support shpc. So I think it's better to use ACPI to
>>>> do it.
>
> Out of curiosity, what OS do you have in mind?
Windows. IIRC, Windows supports SHPC after vista.
>
>
>>>> Currently, we get which device is removed or inserted by reading the I/O
>>>> port
>>>> 0xae00(length: 8 bytes), and _EJ0 method uses I/O port 0xae08(length: 4
>>>> bytes).
>>>> How do we determine this I/O address? Is there any spec to describe it?
>
> As Michael already stated, we can support shpc with acpi.
> What's the point of enhancing adhoc qemu specific hotplug controller
> instead of shpc?
> We've suffered from its adhoc interface, I think.
Do you mean I/O region 0xae00, 0xae08 is not standard. It can work only with
qemu.
Thanks
Wen Congyang
>
> thanks,
>
>>>> Thanks
>>>> Wen Congyang
>>>
>>> Can we discuss these questions on the mailing list?
>>
>> No problem.
>> I have cced qemu mailing list.
>>
>> Thanks
>> Wen Congyang
>>
>