Re: install latest debian 2.4.16 kernelimage has devfs activated, why?
On Tue, 29 Jan 2002, dman wrote:
> On Wed, Jan 30, 2002 at 06:52:07AM +0800, csj wrote:
> | On 29 Jan 2002 11:03:07 -0800
> | Dave Carrigan <dave@rudedog.org> wrote:
> |
> | > Walter Tautz <wtautz@math.uwaterloo.ca> writes:
> | >
> | [...]
> | >
> | > > Just curious to hear other people's opinions on this matter, i.e.
> | > > don't use devfs. It seems to me the debian kernel should have
> | > > CONFIG_DEVFS_FS=n.
> | >
> | > Some people want devfs. Devfs can't be created as a module. Hence, the
> | > logical choice is to build the kernel with devfs support. Nothing's
> | > forcing you to use devfs, even if your kernel has devfs support, and the
> | > overhead is not very much.
> |
> | But, let's say I just want to play with devfs, could I still go back to
> | my old disk-based setup? Could I still boot my old devfsd-disabled
> | kernel after using a devfsd-enabled kernel?
>
> The only hiccup I think you'll see if you do this is :
>
> Suppose you decide you like the devfs name so you edit your fstab to
> use devfs names for all partitions. Now you boot your static-dev
> kernel, and, oops! those device names don't exist.
>
> You could, of course, create static directories in /dev and stick
> inodes there so the old-style kernel works with new-style paths. A
> better solution is to use devfsd with your devfs kernel to provide
> compatibility links and keep the old-style paths in your application
> config files.
>
> (this reminds me, one of these days I gotta boot with a floppy and
> clean out /dev and /tmp since I'm using devfs and tmpfs now)
>
> -D
It should be noted that the devfsd package creates some softlinks to
the old device names at least it did after I installed it. Also
the /etc/init.d/devfsd script checks to see if it should mount dev. Apparently if
the file mount_at_boot in /etc/devfs/ exists it will so this suggests
that booting into a non-devfs kernel should work. As dave has kindly
explained, /dev under devfs is a proc like file system if I understood
him correctly. I.e. it represents an internal kernel data structure.
Strangely enough it is not clear how the softlinks were generated since looking
at /etc/init.d/devfsd shows the file /etc/devfs/symlinks.list is empty in my
case....oh well.
-walter
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