From: Claudio Martins <ctpm@rnl.ist.utl.pt>
To: linux-kernel@vger.kernel.org
Subject: Re: unionfs
Date: Mon, 15 Mar 2004 17:09:11 +0000
User-Agent: KMail/1.6.1
Cc: =?iso-8859-1?q?J=F6rn_Engel?= <joern@wohnheim.fh-wedel.de>,
       Ian Kent <raven@themaw.net>, Carsten Otte <cotte@freenet.de>,
       mszeredi@inf.bme.hu, herbert@13thfloor.at
References: <200403151235.25877.cotte@freenet.de> <Pine.LNX.4.58.0403152233490.19386@raven.themaw.net> <20040315161323.GD16615@wohnheim.fh-wedel.de>
In-Reply-To: <20040315161323.GD16615@wohnheim.fh-wedel.de>
MIME-Version: 1.0
Content-Disposition: inline
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 8BIT
Message-Id: <200403151709.11373.ctpm@rnl.ist.utl.pt>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1233
Lines: 35


On Monday 15 March 2004 16:13, J?rn Engel wrote:
> On Mon, 15 March 2004 22:35:20 +0800, Ian Kent wrote:
> > I don't understand the requirement properly. Sorry.
>
> Depends on who you ask, but imo it boils down to this:
> - Use one filesystem as backing store, usually ro.
> - Have another filesystem on top for extra functionality, usually rw
>   access.
>
> Famous example is a rw-CDROM, where writes go to hard drive and
> unchanged data is read from CDROM.  But it makes sense for other
> things as well.


  If I understand correctly this unionfs feature would also be the cleanest 
way of changing the root filesystem after using an initrd ramdisk on boot. 
Currently the pivot_root call is used to change root but that still implies a 
bit of a hack. You can read about it on this fine paper:

http://www.cis.udel.edu/~zhi/www.docshow.net/linux/ols.zip


  It's also a good read if you want to understand the linux bootloaders and 
the boot process in general.

Regards

Claudio 

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/