libusual interface [was Re: libusual and ub]

[Bill Nottingham]

Pete Zaitcev (zaitcev at redhat.com) said: 
> > [...] So if we're going to build libusual
> > in statically, having the sysfs method to change the bias becomes
> > incredibly important (... as then I can just write to the file from the
> > loader and not worry about it)
> 
> OK, that was a half an hour job. See attached, I'll ask Dave to include
> it and send it to upstream now. Note that there's no bind/unbind here,
> so it has to be set before the back end drivers are loaded.

So... what happens if you have something using one of the backends
loaded,and you want to change what you're using for the second USB
device?

I still think we should just use module aliases and either
don't auto-bind, or separate the aliases by which driver is
best.

> With ub, it is not obvious that the media is indeed a CD-ROM (or a DVD).
> Since ub issues no MODE SENSE command, everything is an array of blocks.
> So, suppose that everything works, how would you know that we're
> installing from /dev/uba or whatever? Do you try to read a header
> from everything that looks vaguely like a block device? That may cause
> interesting effects if you are attached to a SAN, so obviously you do not.
> Very curious.

Generally, the code expects CD-ROMS to be detectable as such - this
is easy enough with IDE or SCSI (and SCSI-using-things.)

Bill