Re: pattern matching in udev

["Chauveau S." <s.chauveau@chello.nl>]

Patrick Mansfield wrote:

>On Wed, Dec 03, 2003 at 08:19:44PM +0100, Stephane Chauveau wrote:
>  
>
>>>>REGEXP "<$bus><$vendor><$id>"="<scsi><ImageMate.*><.*:0:0:\(.*\)>",
>>>>             NAME="mem\1-%n"
>>>>        
>>>>
>>>IMO the pattern matching should be part of the TOPOLOGY plus PLACE. 
>>>
>>>The scsi naming also requires a parent, your example above is only valid
>>>if you have one host adapter connected (or one usb mass storage device
>>>attached), there could exist another sd on *:0:0:0.
>>>      
>>>
>>Not really because my example matches the $bus, the $id and the $vendor.
>>    
>>
>
>There could be another identical scsi device with the same id and vendor.
>
>I thought the PCI sysfs id's were constant for a given hardware, but I'm
>told they can change with PCI hotplug, so the full sysfs path I mentioned
>previously will not be constant across boots with PCI hotplugging.
>  
>

I agree that matching  the vendor is not enough but this is because my 
example is incorrect.
What I call '$vendor' is my example is in fact the '$model'.
The 'ImageMate' is an external USB memory card reader so the PCI or the 
SCSI ids are
not constant and cannot be used at all (except the last bit to 
differenciate the 2 slots on the
card reader). The only way to identify a USB device is to match the 
'model' and the usb
device 'id'

Your remark about having identical devices is especially relevant in 
case of USB (or other
hot-plugable) devices. For example, how could udev handle 2 identical 
USB joysticks?
Ideally, udev should be able to create a device 'js0' for the 1st 
joystick plugged in, 'js1'
for the second, etc.
One accepatble way could be to use the USB topology! the joystick 
plugged in the nth
USB slot would be 'jsn' but that won't work with wireless devices.

>  
>
>>A single method capable of pattern matching on all the available informations 
>>could be used to replace all the methods currently in implemented in udev 
>>(except maybe REPLACE which has a different purpose). 
>>    
>>
>
>-- Patrick Mansfield
>
>  
>
Stephane Chauveau



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