Re: udev: rules using multiple sysfs directories

[Kay Sievers <kay.sievers@vrfy.org>]

On Fri, 2005-04-29 at 01:59 +0100, James Macfarlane wrote:
> On Thursday 28 April 2005 22:44, Kay Sievers wrote:
> > How does:
> >   tree /sys/...
> > of this device look like?
> >
> > What does:
> >   udevinfo -a -p /sys/xxx...
> > print for this device?
> 
> See at the bottom of this message.
> 
> > I never tried this, but:
> >   SYSFS{product/value}
> > may work to go into subdirs?
> 
> Not sure exactly you mean, in terms of syntax. I've just tried  
> SYSFS{1.0/bInterfaceProtocol}  but it didn't seem to work. 
> 
> udevinfo says: "Only attributes within one device section may be used 
> together in one rule, to match the device for which the node will be 
> created."  - that seems to indicate it won't work. 

Yes that is right, but you can specify a path as attribute.
Example:

  [root@pim udev]# tree /sys/block/hda/
  /sys/block/hda/
  |-- dev
  |-- hda1
  |   |-- dev
  |   |-- size
  |   |-- start
  |   `-- stat
  |-- queue
  |   |-- iosched
  |   |   |-- antic_expire
  |   |   |-- est_time
  |   |   |-- read_batch_expire
  |   |   |-- read_expire
  |   |   |-- write_batch_expire
  |   |   `-- write_expire
  |   |-- max_hw_sectors_kb
  |   |-- max_sectors_kb
  |   |-- nr_requests
  |   |-- read_ahead_kb
  |   `-- scheduler
  |-- range
  |-- removable
  |-- size
  `-- stat

This matches:
  KERNEL="hda", SYSFS{queue/iosched/est_time}="*", SYSFS{removable}="*", NAME="test"

> I've had a brief delve into the source and it looks unlikely to work 
> either. It appears to search for attribute names in a pre-existing 
> list, and everything between the curly braces counts as the attribute 
> name (btw, I'm looking at ver 056, which is what my distro (debian 
> testing) uses). So adding '/' is probably not going to work.

Only in the way mentioned above, as a path.

> It walks the tree and breaks out of the loop once all the key-value 
> pairs are matched, but it does all the SYSFS pairs in one loop. So 
> unless all the SYSFS attributes are matched at one level, then the 
> whole rule fails to match.

Right.

But in your case, it may be the easiest to write a PROGRAM-script to
catch your device...

Good luck,
Kay



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