On 31 May 2002 07:17:51 +0100 Alex Hudson <home [at] alexhudson.com> wrote: > On Thu, 2002-05-30 at 23:49, Andrew Basterfield wrote: > > They're there for compatibility but they're no longer used by the > > kernel to identify which device a /dev entry corresponds to. > > Your statment was that it doesn't use them, which it clearly does. Try > reading fs/devfs/base.c; they crop up quite often. The kernel devfs code presents the device's major/minor if the driver also has a old style major/minor interface. It does not, however, 'use' them for device access. It would work without them. That's the point. > Yes, I agree they are there for compatability, no, you cannot do without > them. They are used by lilo and similar userland programs that need to map from a /dev entry to a physical device outside of the kernel. That's all they're there for AFAIK. You could take major/minor support out of devfs and still be able to access the device normally in practically all applications. > > > Devfs is filesystem based. "Device Filesystem" = Devfs. > > > > Devfs is not a filesystem, a filesystem is a system for storing files. > > What do you think entries in /devfs are? They're files. Devfs is a > filesystem. It's code is in linux/fs. Mount shows it as type 'devfs'. > > Trying to argue procfs is less a filesystem than ext2 is fairly > non-sensical. Procsfs, devfs, usbfs, devpts et al don't exist on media, therefore they are virtual. They also offer only limited support for normal filesystem operations making them IMHO 'less of a filesystem'. > Everything is a virtual filesystem, it's even called the VFS. VFS is not a filesystem and it doesn't pretend to be, it's an abstraction layer which replaced the original Minix-only fs code in early Linux kernels, making all filesystems and pseudo-filesystems look a bit like Minix to the lower levels of the kernel. Just because a filesystem sits behind VFS doesn't make it virtual. The filesystems are real, pseudo-filesystems and VFS are virtual. --Andrew -- sparc sun4c stuff: http://www.lostgeneration.freeserve.co.uk/sparc PGP key for list [at] lostgeneration.freeserve.co.uk: http://www.lostgeneration.freeserve.co.uk/list.freeserve.co.uk.asc
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