Re: vnd.c 1.254

[John Nemeth <jnemeth%cue.bc.ca@localhost>]

On Jan 17,  9:37pm, Robert Elz wrote:
}
}     Date:        Sun, 17 Jan 2016 14:49:23 +0100
}     From:        Manuel Bouyer <bouyer%antioche.eu.org@localhost>
}     Message-ID:  <20160117134923.GA2010%asim.lip6.fr@localhost>
} 
}   | I mean, vnconfig -l (without other arguments) has been showing available
}   | devices for a long time:
} 
} Yes, I know, and agree, it has ... but that is only possible if it
} is possible to rationally enumerate the available devices.   When there
} were a fixed (small) number, it made sense.  That is no longer the case.
} 
} Do you really want it to list 4 billion free vnds ?

     Obviously not, unless somebody was silly enough to create 4
billion /dev entries, which is likely to cause other problems.

} Using what is in /dev is incorrect (always was) as /dev is just a
} convention (and particularly is not reliable when chroots are in use).

     It may be "just a convention", but it is also the best
approximation.

}   | this is a major behavior change, which may well break existing setups.
} 
} True, but there is little alternative, unless you'd like to return to
} the pre cloning days.   It can stay as it is now, listing free devices
} up to the highest used (but that really is hard to explain and makes
} little sense, and as you have observed, is not very reliable) or I guess
} we could just add a 
} 
} 	for (n = highest_found; ++n < highest_found + 4; )
} 		printf("vnd%d: not in use\n", n);
} 
} after it finishes printing, just to list a few more free ones.
} 
}   | You remove existing and working functionality to fix a marginal backward
}   | compatibility issue ?
} 
} Not marginal at all, and backwards compat has always been one of NetBSD's
} prime objectives.
} 
}   | But removing this functionality is breaking
}   | backward compat, in a much more important way.
} 
} Actually, I doubt it.  I suspect some other issue is the problem here,
} and the change to vnconfig -l is just confusing the issue.

     Possibly.

}   | we *are* already running an up to date vnconfig, dammit !
} 
} Ah, OK, I misread your description (I thought you meant one from 7.0)
} 
}   | not until this problem is fixed. Breaking XEN3_DOM0 support is a real
}   | problem.
} 
} Agreed, we need to work out what is causing that vnconfig to fail.
} 
}   | Unfortunably it's transient.
} 
} That does make it difficult to debug.
} 
}   | After a view vnconfig manipulations the
}   | problem is gone for me (and vnconfig -l again show all devices,
}   | used or free).
} 
} All 4 billion of them?
} 
}   | cd_ndevs is now at 8 (checked with gdb against /dev/mem)
} 
} Then at some stage you had vnd7 configured.
} 
}-- End of excerpt from Robert Elz