Re: [ANNOUNCE] udev 0.1 release

Lars Marowsky-Bree
2003-04-11T22:27:28Z

On 2003-04-11T15:30:21,
Steven Dake <sdake@mvista.com> said:

> There is no "spec" that states this is a requirement, however, telecom
> customers require the elapsed time from the time they request the disk
> to be used, to the disk being usable by the operating system to be 20 msec.

Heh. Yes, I've read that spec, and some of it involves some good crack smoking
;-) The current Linux scheduler will make that rather hard for you, you'll
need hard realtime for such guarantees.

> Its even more helpful for their applications if the call that hotswap
> inserts blocks until the device is actually ready to use and available
> in the filesystem. Another requirement of any system that attempts to
> replace devfs would be this capability (vs constantly checking for the
> device in the filesystem).

Uh. Can you please clarify?

You want open(/dev/not_there_yet) to block until /dev/not_there_yet is
inserted? But if it is not inserted, the device file does not exist yet, so
the open() will simply return a ENOENT.

The application (or a library, providing this capability you want) could
interact with the hotplug subsystem to be notified when this device is
inserted.

Sincerely,
Lars Marowsky-Brée <lmb@suse.de>

--
SuSE Labs - Research & Development, SuSE Linux AG

"If anything can go wrong, it will." "Chance favors the prepared (mind)."
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