DragonFly kernel List (threaded) for 2004-04
Re: devfs vs udev/hotplug
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.
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
* Aggressive device enumeration. Multiple concurrent policy execution
* 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.