Re: [PATCH] VM-Tool: C-based Xen management tools

[Anthony Liguori <anthony@codemonkey.ws>]

Mark Williamson wrote:

>The current implementation sidesteps all these by specifying port IDs.  e.g. 
>port 1 on my root hub always belongs to VM1 (when running), port 2 on hub 3 
>always belongs to VM2 (when running), etc.
>  
>
Yeah, I think we'll always have to support this as a fallback option.

>>Not sure the best solution here.  One of the reasons I've held off on USB.
>>    
>>
>
>For comparison, do you know what abstraction other systems do?  Do they assign 
>ports or associate devices with VMs?
>  
>
Not sure.  The only thing I know that does USB virtualization is VMware 
and I've not played with that feature (I think it's a relatively new 
feature).

udev/namedev have to deal with this to ensure that devices have a unique 
(and consistent) /dev entry.  It currently uses a tiered approach to 
determine exactly what the device is.  It's not perfect but it works 
reasonably well.  The best link I could find explaining it with a quick 
google is:

http://www.gentoo.org/doc/en/udev-guide.xml

A GUI would be really handy for PCI/USB because it would provide an easy 
way to pick devices by name (instead of specifying an series of 
identifiers/bus/etc in the config).

>The latter is definitely an attractive option...  If we added support for both 
>ways of doing things, paranoid people (or people with weird devices!) could 
>use the port specifiers, whilst others used device IDs.
>  
>
I agree completely.  I'm currently adding proper documentation to 
vm-tools but after that's done I'll add USB virtualization and try to 
implement a mechanism to select by device ID and push out another 
version to the list.

Regards,

-- 
Anthony Liguori
anthony@codemonkey.ws



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