Re: [ANNOUNCE] udev 0.1 release

Steven Dake
2003-04-11T22:31:12Z

Lars Marowsky-Bree wrote:

>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 quite easy to do if you are not dependent upon spawning an entire
process to execute the insertion and creation even of the device node.

>
>
>
>>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>
>
>
>