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From: mark@roissy.umd.edu (Mark Sienkiewicz)
Newsgroups: comp.os.386bsd.development
Subject: Re: Some ideas on the driver interface (yet another idea!)
Date: 19 Mar 1993 15:59:13 GMT
Organization: University of Maryland
Lines: 70
Message-ID: <1ocqkh$lm4@umd5.umd.edu>
References: <1993Mar17.122612.5929@neptune.inf.ethz.ch> <1o9l9u$nn@tricky.wft.stack.urc.tue.nl> <1993Mar19.074044.18995@gmd.de>
NNTP-Posting-Host: roissy.umd.edu
In article <1993Mar19.074044.18995@gmd.de> veit@mururoa.gmd.de (Holger Veit) writes:
>
>Why would *you* want to modify *default* protections in a system? There are
I find that defaults are _frequently_ not correct for my uses. I should
be able to set them up the way I like. The current system allows me to
do this with well known commands like chown and chmod. A replacement
system should have a similar functionality.
>A proper fs has something like
>the concept of inodes, dynamic allocation of name slots/inodes, thus making
>links and named pipes (and perhaps subdirectories) available.
I totally agree with this. I suggest that subdirectories are not optional.
To add to that, though- I also suggest that _storing_data_ is not optional.
I.E. /dev/fd0a may be a floppy disk, but /dev/fd0a.note may be a file that
contains a note for users of that device.
Here is an idea I submit for discussion:
Keep your devices disk based, but don't use major/minor numbers as we
have them now.
There is enough space in the inode that you could be storing a string
instead of a major number. When you open a device file, it could fetch
this string from the inode and look it up in a table in the kernel. Cache
the inode-to-device lookup, and you have the equivalent of a dynamically
assigned major number.
Then instead of
mknod /dev/com1 c 35 0
I might
mknod /dev/com1 c cgd_com 0
mknod /dev/sd0a b julian_scsi 0
^^^^^^^^^^^
the _name_ of the driver instead of some arbitrary
number
This idea has some advantages:
technical:
- it solves the problem of limited major numbers by using device
names (the thing that started this whole discussion)
- it gives _permanence_ to devices and the changes you make to them
- it
- it can _not_ get confused if you boot a different kernel
political:
- it gives both sides of this discussion the features/functionality
that they want (IMHO)
Disadvantages are:
techical:
- it doesn't work over NFS (neither does anything else)
political:
? you tell me :)
>Holger
Mark.