Re: Where can I find some tutorial or manual on how to use xenstore?

[Nick Logan <nick_logan@symantec.com>]

Ewan Mellor wrote:

>On Wed, Jun 28, 2006 at 04:20:51PM +0100, Nick Logan wrote:
>
>  
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>>Ewan Mellor wrote:
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>>>On Wed, Jun 28, 2006 at 02:38:15PM +0100, Nick Logan wrote:
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>>>>The driver was started outside of xend, using a varient of Jacob's 
>>>>buscreate program to set the necessary values in xenstore. As this a 3rd 
>>>>party driver, I'm looking for a solution that does not involve xm or 
>>>>xend changes, if that's possible. I'll take a look at the blktap patches 
>>>>to see if that helps.
>>>>  
>>>>
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>>>Xend is explicitly bringing the devices back up on restore.  If you
>>>deliberately bypass it, then you are going to have to do that bringup
>>>yourself.
>>>
>>>Ewan.
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>>I guessed that would be the case. The bringup for a restore would be 
>>quite straighforward but more complex for migration. Has anyone 
>>suggested hooks for xend to deal with 3rd party drivers so that it could 
>>initialise and restore devices that are supported by these drivers?  
>>This would enable new drivers to be implemented without changes to xend.
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>
>One would have to write a device handler that parsed generic config, and then
>passed it through to the store unaltered, and then have hotplug scripts that
>could cope with this unparsed config.  At the moment, the driver backends do
>special-case things like generating a MAC address when none is supplied,
>converting device names to their major:minor, that kind of thing.  There isn't
>a generic device path; adding one wouldn't be hard.
>
>Ewan.
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>
Can I just confirm what your proposal is:

Add a generic device config to the xm config file that would contain the 
driver id, virtual device, physical device .....
Add a generic device handler to xend that would pass the unparsed 
generic config through to xenstore.
Add a hotplug script that would parse the unparsed config in xenstore 
and start the driver.
When saving a domain, xend would save the generic device config.
xend would call restore for the generic devices.

If  that's correct, I'll find some time to investigate how this could done.

Nick