devfs vs udev/hotplug

[esmith]

uDSE

It seems there is one other approach that is very similar to udev called 
"User-Space System Device Enumeration" or uDSE. The uSDE was built in 
response to a set of telco and embedded community requirements. The uDSE 
is based around the idea of policies.

http://sourceforge.net/projects/usde

According to one of the developers, issues that uDSE addresses that udev 
might not are:

* The embracing of all device types with no specialization or limitation.
* The ability to have total control over the handling a device via 
external policy programs. Policy programs are invoked with a formal 
command line and description of the event that caused there invocation.
* The "service container" concept. A device is classified (or recognized 
by a pattern match) and this raises an (queued) event which is caught by 
a configurable "service container". The container is an ordered list of 
handlers that process the device.
* Event queuing and aggregation. Minimizing the number of program 
invocations (fork/exec) is critical in embedded environments - small 
processors.
* Aggressive device enumeration. Multiple concurrent policy execution 
and management.
* Device information persistence is a function of device policies, not 
the enumeration framework.There are many situation where persistence is 
not an issue at all or only in specific cases (like disks). Why always 
pay for the memory/disk, for persistence, when it is not (always) necessary?
* Transactional protection of multiple configuration files is necessary. 
Multiple configuration files must often be modified in unison and 
insurance is necessary that an accurate and correct set of data is used 
when processing devices.