Re: [PATCH] kdevt-diff

[Joel Becker <Joel.Becker@oracle.com>]

On Mon, Apr 14, 2003 at 11:00:27AM -0700, Linus Torvalds wrote:
> Well, the thing is, we absolutely _do_ need to have the 8+8 split, in
> order to make old devices look the same old way for old binaries.

	Yes, and I support this 100%.

> The 16+16 split is not strictly necessary, but Andries pointed out to me
> that there are filesystems etc external storage that only support a 32-bit
> opaque dev_t, so we'd need to marshall the device number _some_ way for
> them anyway, and having a standard way to do that is better than having
> everybody come up with their own variations.

	Sure, but it's a marshall, not a reality.  One of the reasons
for choosing 64bits is that we can have large spaces for large things.
If a driver happens to get a number in the 16:16 space (or the 12:20
space, which I prefer as well), then it could run out of space and end
up with the multiple major problem.
	True, a truly dynamic scheme could make all of this irrelevant,
but I was just postulating that complexity isn't strictly necessary.
	I guess it is a trade off.  Do all devices greater than 8:8
become 32:32 and merely are masked to 16:16 on limited filesystems, or
do all devices smaller than 16:16/12:20 appear the same on all
filesystems, limited or not?

JOel

-- 

"You can get more with a kind word and a gun than you can with
 a kind word alone."
         - Al Capone

Joel Becker
Senior Member of Technical Staff
Oracle Corporation
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127