Messages in this thread |  | | Date | Tue, 15 May 2001 01:43:57 +0200 | From | Jan Niehusmann <> | Subject | Re: LANANA: To Pending Device Number Registrants |
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On Mon, May 14, 2001 at 11:21:00PM +0100, Alan Cox wrote: > You can make it a string if you like but at the end of the day > has to be an opaque handle. For constant devices it also has to be > a constant name. Otherwise the /dev file I archived with the corporate > backup system turns out to be a different device when I restore the > box after a problem and I reformat the wrong disk...
Why can't we configure this in user space? I think of something like /etc/major-numbers. We could then tell the kernel at module load time what major number to use for a given driver.
The corporate backup system then only needs to restore /dev and /etc/major-numbers at the same time.
I don't think this is the ideal solution. But it has some nice properties:
- no policy in kernel. Neither device names nor numbers are hard-coded - no daemons needed, only some simple startup scripts - no special filesystems needed, /dev is simple tar-compatible directory - everybody can add drivers to his system as he wants, without the need to register a number. One entry in a config file is enough - every single system only needs as many major numbers as there are drivers - so even 256 majors should be enough in most cases. (this may be limited by the fact that the existing numbers should be recommended as standard entries in /etc/major-numbers to stay backward compatible)
Of course there are disadvantages, the biggest problem I see are drivers compiled into the kernel. They need to get their major number from the command line, I think, which is pretty ugly.
Perhaps the above is pure bullshit and my proposal is not working for serveral reasons. But I think we should try to define our requirements to the device numbering/naming system, and then find a solution that meats these requirements - the final reason for choosing one solution should be a technical one, not personal preference.
Jan
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