Path: utzoo!attcan!uunet!mailrus!cornell!uw-beaver!ubc-cs!alberta!atha!lyndon
From: lyndon@cs.AthabascaU.CA (Lyndon Nerenberg)
Newsgroups: comp.unix.questions
Subject: Re: Why /etc/mtab? (was: Example modification of /etc/mtab wanted)
Message-ID: <1929@aurora.cs.athabascau.ca>
Date: 5 Jun 90 17:03:57 GMT
References: <1678@trlluna.trl.oz> <1918@aurora.cs.athabascau.ca> <BZS.90Jun2160829@world.std.com>
Organization: Athabasca University
Lines: 36

>It goes way back to the early Unix days, V6 on the PDP-11 certainly
>had /etc/mtab. With a maximum of 64KB for the kernel you made
>trade-offs, one of Unix's early plus's was how much it used facilities
>outside the kernel to get things done. Design goals were also
>compelling.

>Of course, in this day and age it seems like a minor savings, but you
>could probably find dozens of things like this to put in the kernel if
>you looked around. The bloat would start to get real (why not store
>environment variables in the kernel so children can set parent
>processes? How about the password/group file? host tables? Heck,
>everything YP manages? etc etc.)

[ and more stuff about saving precious kernel space ]

To which Lyndon replies:

	Barry, the information is *already* in the kernel, inside
	the mount tables.

I was wondering what it was that was being saved by duplicating the
kernel information in a file. Tom Truscott's answer was what I expected
to hear, but you never know ... :-)

BTW - I like the idea of implementing /etc/mtab as /dev/mtab. The big
problem I have with /etc/mtab is that it is usually completely out of
sync with respect to the contents of the kernel's mount tables (primarily
due to NFS failures). In these days of almost-reliable network file
systems, I don't think we should be second guessing in user space something
as intimately related to the kernel as the mount table.

-- 
      Lyndon Nerenberg  VE6BBM / Computing Services / Athabasca University
          {alberta,cbmvax,mips}!atha!lyndon || lyndon@cs.athabascau.ca
         Sendmail has been described as the largest program yet created
                 that does absolutely nothing. -- Mr. Protocol