Messages in this thread |  | | Date | Tue, 2 Jul 1996 11:40:00 +0300 (EET DST) | From | Linus Torvalds <> | Subject | Re: SCSI device numbering (was: Re: Ideas for v2.1 |
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On Tue, 2 Jul 1996, Leonard N. Zubkoff wrote: > > The whole idea of /proc/dev and completely dynamic (major,minor) assignments > has been discussed before, and I recall there were relatively few problems with > it. Am I missing something fundamental here?
No, some of the naming issues can be handled with /proc/dev, but there are a few problems:
- the "other" things about naming, not just the device number. That includes owner and protection information (we do NOT want the kernel to set policy), and the ability to map the devices to multiple different names (/home/ftp/dev/xxxx). - hardcoded device numbers: notably the root device - NFS imported filesystems for machines - system working without /proc
The /proc filesystem is not meant to be able to handle complexities like this: it's meant to be a simple window to the kernel. It _looks_ trivial to have the /proc filesystem have default protections for the files, and then let the administrator override them with chmod/chown, but it gets very non-trivial indeed when you want to mount the /proc filesystem on multiple points on a machine at the same time (which _is_ possible, and _should_ be possible).
There aren't that many hardcoded device numbers (I can't think of any but the root device right now), so that should be reasonably easy to take care of some way. So if that was the only problem I wouldn't worry.
The most important issue is probably that we do _not_ want to FORCE people to use the /proc filesystem if they don't want to, and at boot-time, for example, we want to be able to do basic housekeeping without /proc mounted (and that definitely includes fsck'ing the root filesystem while it's read-only mounted, and probably other disks too).
In general, I don't really like /proc/dev/ - it implies giving policy to the kernel in one way or another (actual naming, permissions, placement, bootup etc). Too much policy by far. We want to avoid policy decisions as far as humanly possible.
Linus
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