Re: [Qemu-devel] USB Hostport Differences

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 06/10/2012 12:51 PM, Erik Rull wrote:
> Hans de Goede wrote:
>> Hi,
>>
>> On 06/08/2012 10:56 PM, Erik Rull wrote:
>>> Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 06/08/2012 06:33 PM, Erik Rull wrote:
>>>>> Hi all,
>>>>>
>>>>> when assigning USB host devices to a guest using the hostport option,
>>>>> there seem to be different formats, when calling info usbhost:
>>>>>
>>>>> - On my vanilla kernel linux there is a hostport format e.g. "1.5" or
>>>>> "1.2"
>>>>> - On my Debian 6.0 full blown linux there is a hostport format "2" or
>>>>> "4", that means, there are no dots and only one number
>>>>>
>>>>
>>>> Hmm, is this on the same machine, with the usb devices hooked up the same
>>>> way? Normally these differences come
>>>> from there being hubs in the chain, ie "2" or "4" indicate devices plugged
>>>> directly into a root hub,
>>>> "1.5" and "1.2" mean devices plugged into a hub, which itself is plugged
>>>> into root port "1"
>>>>
>>>> Regards,
>>>>
>>>> Hans
>>>
>>> No it's on different machines - first with Intel Hardware, second with
>>> AMD Hardware. I have no hubs attached, I use the ports that are offered
>>> directly on the mainboard (EPIC Nano Connectors / ATX rear side panel).
>>> On all other Intel systems I see the same effect with the "1.x" ports.
>>> Only the AMD system shows the single numbers.
>>>
>>
>> Those would be sandy bridge or newer Intel machines then, these no longer have
>> an EHCI usb controller + UHCI companion controllers, but only an EHCI
>> controller,
>> so the root ports are USB-2 only. In order for USB-1 devices to still work the
>> chipset has an integrated USB-2 hub (which can handle USB-1 ports), of you do
>> lsusb you should see something like this in there:
>>
>> Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
>>
>> Which is why you get the 1.x for the motherboard ports, because there is
>> actually
>> a hub between the root hub and the ports.
>>
>> Regards,
>>
>> Hans
>>
>
> Hi Hans,
>
> thanks for the explanation - so I will try to find out which way of USB handling is given on the current system and then add the correct hostport filters.
>
> Is there an easier way of finding this kind of architecture automatically beside grep'ing for such a Hub?

Not that I know of I'm afraid.

Regards,

Hans