Subject: Re: dev_t changes & partitions
To: Charles M. Hannum <>
From: Bill Studenmund <>
List: tech-kern
Date: 01/14/1998 17:41:04
On Wed, 14 Jan 1998, Charles M. Hannum wrote:

> > Hmm. Well, I'd still vote we change the minor split when we change
> > dev_t's. That way we rebuild devices only once. :-)
> I'm compelled to point out that, with my proposal, none of the device
> numbers change at all until we decide to do an actual renumbering.
> The two steps are largely orthogonal -- and both pretty trivial.

I agree that the changes are orthogonal (except that we won't want to
change the number of partitions until we have a larger minor field :-),
and that they don't really involve much code changing (especially changing
the partition field).

But with any of the changing schemes, how do we tell a changed dev_t from
an unchanged dev_t? If it's a 16-bit or 32-bit dev_t seems like an easy
clue to me.

When we're talking about renumbering, we could just renumber everything to
numbers we haven't used yet. But when it comes to changing the
unit/subunit split, every idea I've heard (including the ones I've cooked
up) have been shot down with, "let's do it when we go to 32-bit dev_t's."
I think it'll be easiest to at least do the unit/sub-unit split with the
switch to 32-bit dev_t's.

I think I missed your proposal for re-numbering. I did see the one for
going to 32-bit dev_t's.

Take care,