Re: PROPOSAL: /proc/dev

Kevin Lentin (kevinl@cs.monash.edu.au)
Sun, 4 Jan 1998 12:00:04 +1100

On Fri, Jan 02, 1998 at 01:17:58PM +1100, Richard Gooch wrote:
> If a process tries to open() an entry in /dev which does not exist,
> devfs passes the name of the entry to kerneld. It is up to kerneld to
> convert filenames to modules (i.e. "ttyS{0,1,2,3}" to "serial").

I hope there is a suitable wildcard (or filename globbing) scheme. This
would be especially useful for disk devices. Floppy disk devices in
particular are quite numerous.

> The system boot script checks it's /dev protections database and uses
> chown(2) and chmod(2) to modify permissions. If an entry does not
> exist, the script must first call mknod(2) which will create a
> "placeholder" entry. This placeholder will appear to have major&minor
> of -1,-1 or some such. When chmod(2) is called the ctime is updated.
>
> When a device driver registers a device entry and a placeholder entry
> is already there, the entry is filled in and the major&minor will
> appear to be 0,0.

Hmmm - /dev/ ends up being a script you have to keep up to date instead of
a driectory. Although no majors and minors which is the major (sorry) win.
And many people around here would patch their kernel anyway to change the
defaults. Or the kernel could #include a standard file (eg src/.devices) if
it is there to set sysadmin defaults. Either way it's a system maintenance
issue (or a one line kernel change and a sysadmin issue).

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