[cgl_discussion] Re: parenting of devices

Steven Dake sdake at mvista.com
Wed Jul 9 12:41:30 PDT 2003


Pat,

Let me do a little research.  I have a bad headache and have a little 
trouble concentrating right now :(

I'll respond later when I have taken a deeper look

Thanks
-steve

Patrick Mochel wrote:

>>It is true that one level of parenting is not particularly useful. It is 
>>desireable to know, however, that a scsi disk is connected to a 
>>particular fibre channel adaptor, and that fibre channel adaptor has a 
>>host IEEE ID which is unique (even if positions change). It is also 
>>desireable to know that a cdrom is attached to a USB device instead of a 
>>SCSI device for the execution of policy methods.
>>    
>>
>
>The device path is already there and easily obtainable. When a device is 
>inserted, /sbin/hotplug is called to notify userspace of the insertion. 
>The device path is passed, but this call is largely useless WRT naming.
>
>When the device is registered with its class(es), /sbin/hotplug is called 
>again with the path to the class object in sysfs. Within that class 
>directory should be a symlink that points to the device's physical 
>directory. From this symlink, the physical path of the device can be 
>derived (since the symlinks are made by traversing the parent objects to 
>the root). 
>
>All the pieces should be there, with the exception of a unique identifier 
>for a device in the form of an attribute. But these, as you mentioned, can 
>be obtained via other means for the time being.
>
>Will this work for you? 
>
>
>	-pat
>
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