Subject: Re: /kern/kernel
To: NetBSD-current Discussion List <firstname.lastname@example.org>
From: Gandhi woulda smacked you <email@example.com>
Date: 09/16/1998 00:52:24
On Mon, 14 Sep 1998, Greg A. Woods wrote:
* [ On Mon, September 14, 1998 at 08:23:55 (-0400), der Mouse wrote: ]
* > Subject: Re: /kern/kernel
* > The problem is, / is mounted read-only. To remount it read-write,
* > userland does "mount -o update /dev/whatever /". This doesn't work,
* > because when the kernel looks up / to get the mounted-on vnode, it gets
* > a different vnode from the one the root device is currently mounted on.
* I believe this is why SCO Xenix (and possibly other implementations)
* have a /dev/root and /dev/rroot. These are virtual devices that always
* point at the "real" one -- i.e. the one set at boot time either because
* that's where the kernel was loaded from, or that's where the user
* specified for the equivalent of a "boot -a". That way "mount -o
* update,rw /dev/root /" is always correct. Although if I remember right
* finding out what the real root disk is from user-land is left as an
* exercise to the user.....
/dev/root and /dev/rroot were originally hard-links to the "real"
devices under SVRx (0 <= x < 4). How they got there, I'm not sure,
but ls -l showed them to have the exact same major and minor numbers
as the disk and partition (if possible) from whence they were booted.
SCO's implementation must be much more bloa\aolb/slick than that.
Friends don't let friends use Microsoft.