Re: [Libcdio-devel] OSX SCSI MMC commands via PLScsi?

[R. Bernstein]

Couldn't a program that needs to issue a MMC command (via this SCSI
passthrough mechanism) just try to do an unmount just before it opens
the device? Would this work?

Steven M. Schultz writes:
 > 
 > On Sat, 25 Mar 2006, R. Bernstein wrote:
 > 
 > > I came across this interesting link to a program called PLScsi
 > >   http://members.aol.com/plscsi/mac/
 > > 
 > > But the usual OSX caveat applies. From http://members.aol.com/plscsi/mac/
 > > 
 > >    Second nastiest remaining technical issue are the significant side
 > >    effects of the open/ close in the launch-open-ioctl-close-exit
 > >    sequence that's fundamental to the idea of plscsi at the command
 > >    line.  In Mac OS X, open works only if preceded by diskutil unmount
 > >    (that's "unmount" not "umount"), and close provokes automount, ouch.
 > 
 >      That sounds very much like the same problem that has come up in the
 >      past - that of getting an 'exclusive access reservation'.  Without
 >      that you need to be the owner of the device, issue an unmount, do your
 >      command, but then the kernel/system goes and remounts the device  when
 >      the program closes.
 > 
 >      Maybe not 100% the same thing but it sure sounds similar/familiar.
 > 
 >      OSX is an interesting system but its I/O model sure strikes me as
 >      being baroque - not as nice as BSDi ;)
 > 
 >      Cheers,
 >      Steven Schultz
 > 
 > 
 > 
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