Re: Does sysfs really provides persistent hardware path to devices?

[OSDL <torvalds@osdl.org>]

Andrey Borzenkov wrote:
> 
> As far as I can tell sysfs device names include logical bus numbers which
> means, if hardware is added or removed it is possible names do change.

Absolutely.

The fact is, the kernel _cannot_ give persistent names to devices, because
it is simply not a problem that is solvable with the resources the kernel
has access to.

For persistent naming, you need (a) user policy and (b) stable storage,
neither of which the kernel has. 

GregKH has a "udev" setup that plugs into /sbin/hotplug and uses sysfs
to implement stable naming. So sysfs is part of the picture, but it's
not the whole answer.

> the point is - I want to create aliases that would point to specific
> slots. I.e. when I plug USB memory stick in upper slot on front panel I'd
> like to always create the same device alias for it.

Right: what you're asking for is persistent per-device user policy.

                Linus