Re: removable media revalidation - udev vs. devfs or static /dev

Olaf Hering
2004-01-07T09:45:24Z

On Sat, Jan 03, Jens Axboe wrote:

> On Sat, Jan 03 2004, Andrey Borzenkov wrote:
> > > Is there really no way to get a media change notification from ZIP or
> > > JAZ drives?
> >
> > If anyone knows please tell me - I will put it into supermount ...
> >
> > AFAIK in case of SCSI this is impossible simply by virtue of protocol - SCSI
> > device is not initiator. So you need something to poll device for status.
> > That is usually done on device open except in this case you can't open
> > because you do not yet have handle.
>
> You could queue a media notification request for long periods of time,
> being completed by the drive when a media change happens. At least mmc
> allows for this, doubt anyone has ever done it.
>
> So yeah, poll...

Poll how? "kmediachangethread"? Or polling in userland? The latter would
(probably) lead to endless IO errors. Not very good.
If I understand the Darwin sources correctly, a polling is used. But I
havent looked hard how they do it.

--
USB is for mice, FireWire is for men!

sUse lINUX ag, nÜRNBERG