Re: Larger dev_t

Pjotr Kourzanoff
2001-03-28T11:53:12Z

On Tue, 27 Mar 2001, Linus Torvalds wrote:

> ... lots of stuff removed ...
>
> So in /dev, there are two problems: we are getting painfully close to
> major numbers with 8 bits, and we've run out of minors several times. In
> fact, a lot of the reason for the dearthness of major numbers is the fact
> that we use multiple majors for some stuff that really wants many minors.
>

Well, one solution to this on the long term comes quite naturally:
make major/minor separation a policy, i.e., as in network/host
IP numbers. That is, in addition to 32-bit dev_t there would
be a 32-bit devmask_t that when &-ed with dev_t would yield the
major. The default, for compatibility reasons will be devmask of 255
(or -1+1<<12). For example, all floppies would fall into 2/8 major
(using IP address notation). Obviously, all this is not advantageous
on the short term, but in the absence of better ideas, this can give
some flexibility when allocating/shifting to new majors/minors...Of
course, namespaces approach is even better, but when will all drivers
be converted to support them?

Cheers,

Pjotr