Unable to mount / in read - write mode

[mdh]

--- On Tue, 11/4/08, Popof Popof <popof.fpn at gmail.com> wrote:
> From: Popof Popof <popof.fpn at gmail.com>
> Subject: Unable to mount / in read - write mode
> To: "FreeBSD Questions" <freebsd-questions at freebsd.org>
> Date: Tuesday, November 4, 2008, 1:57 PM
> Hi,
> I recently tried to update my FreeBSD 6.0 to FreeBSD 7.0.
> I don't know where but I made a mistake and I am always
> booting on the 6.0
> kernel.
> The problem is that I have an error during boot process:
> 
> mount option <rw> is unknown
> > mount: /dev/ad0s2a : Invalid argument
> > Mounting root filesystem rw failed, startup aborted
> > Boot interrupted
> 
> 
> Its seems that tools have correctly upgraded (man mount let
> me see that I
> use the FreeBSD 7 version of mount) but not the kernel.
> 
> Does someone has an idea to allow me to use my filesystem
> in read write mode
> ?

This seems to be a problem with the mount command.  Why do you feel the kernel may be at fault?  If the kernel can get to mount, then it has obviously already mounted / (though possibly in read-only mode, which is something you should let us know...)
There is also not necessarily a corrolation between a man page and the actual binary.  Check the binary's modification time and such for better detail here.  Beyond that, try running the mount command manually from the command line after booting from a CD or in single-user mode, if single-user mode works.  

- mdh