On Thu, 28 Dec 2000, Chuck Silvers wrote:

: actually this change is not completely backward compatible.
: if someone has created device nodes with those upper minor bits set
: (ie. for /dev/sd385792385a or whatever the number turns out to be),
: then those device nodes would no longer refer to the same device
: after this change.  to me, this falls into the same category as
: the problem that __BROKEN_CONFIG_UNIT_USAGE indicates, that we make
: assumptions about the usage of device minor numbers.  in this case
: the assumption is that the upper bits of the minor number have not
: been used by anyone anywhere.

: the only completely backward-compatible way to increase the number
: of partitions is to create a new device major number for each current
: device major that uses part of its minor as a partition.

There comes a point where supposition leads into ludicrous situations, and
this is one of them.  If the extra partition bits are placed sufficiently
high in the minor number to provide a reasonably large number of units (say,
16384 drives?), someone will have had to create nodes with ridiculously
large unit numbers to conflict with them.

We don't control third-party, nonintegrated patches that may reuse minor
bits for some other purpose--and in situations like these, we don't have to
care.  Such third parties can update to match us, or contribute the changes
to the mainline.  That's not our concern.

We have already been down this road of discussion some time ago and came to
the conclusion that reusing higher bits of the minor number for further
partitions was perfectly acceptable.

: I think we should consider a logical volume manager design
: rather than continuing to fiddle with fixed-partitioning.

That's not addressed by this thread, and does not help people who want this
feature right now.

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