Re: 64-bit kdev_t - just for playing

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

On Fri, Apr 11, 2003 at 01:53:07AM +0200, Roman Zippel wrote:
> So we do break compatibility! Wow, it really took quite some time until 
> someone confirmed this...

	No, the current patch DOES NOT BREAK compatibility.  Device
numbers from 00:00 to FF:FF are not munged in any way.  As long as
regular drivers don't expect anything else (eg, a new scsi driver that
uses a new larger major), nothing is broken or changed.

> The current numbering matches the naming, 0x0301 is /dev/hda1, 0x0802 is 
> /dev/sda2 and 0x4103 is /dev/sdq3, the proposed patch does change the 
> numbering _and_ naming policy.

	The proposed patch changes none of it.  Folks have proposed
other changes based upon it, but Andreas' patch as it stands (at least,
last time I looked at it) does not break this.

> This may be true in the kernel, but you move all the compatibility 
> problems into user space and so we just added another ugly emulation 
> layer.

	Naming is entirely a userspace problem.  It is also an extremely
hard problem.  Consider that the UK folks will want /dev/disc and the US
folks will want /dev/disk.  That's before we even approach persistent
naming.

> Oh, I do listen, you can be sure of that, but what am I supposed to so, 
> when it even takes weeks to get a clear answer about something simple as 
> compatibility? When I ask questions, I get evading answers, when I say 
> it's broken, I get silence, what else can I do?

	I will repeat:  The patch does not break compatibility, and any
discussion of new device spaces based on the larger number have been
theoretical.  If you had read the patch, you would have seen this.

> Producing a patch isn't that difficult, but I'd rather be interested, if 
> there is even interest in such a patch? I already got not a single comment 
> about the last patch.

	Propose a dynamic system.  Show us your code.  Until you do,
do not clutter the simple task of "expand the size of dev_t" with the
orthogonal task of "how do we use this new dev_t".

Joel

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