From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pw0-f43.google.com (mail-pw0-f43.google.com [209.85.160.43]) by ozlabs.org (Postfix) with ESMTP id 97A24B7CEA for ; Wed, 20 Jan 2010 13:32:17 +1100 (EST) Received: by pwj11 with SMTP id 11so3172069pwj.2 for ; Tue, 19 Jan 2010 18:32:15 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20100119140600.GH16182@darwin> References: <20100119095024.GD16182@darwin> <20100119102026.GF16182@darwin> <20100119140600.GH16182@darwin> Date: Wed, 20 Jan 2010 10:32:15 +0800 Message-ID: Subject: Re: mount ramdisk rootfs /etc directory to jffs2 filesystem. From: Johnny Hung To: Matthias Kaehlcke Content-Type: text/plain; charset=ISO-8859-1 Cc: kernelnewbies , "linux-mtd@lists.infradead.org" , Ricard Wanderlof , "linuxppc-dev@lists.ozlabs.org" , "linux-embedded@vger.kernel.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 2010/1/19 Matthias Kaehlcke : > El Tue, Jan 19, 2010 at 02:17:22PM +0100 Ricard Wanderlof ha dit: > >> On Tue, 19 Jan 2010, Johnny Hung wrote: >> >>> Okay, I think the steps is below if my rootfs is ramdisk and configure >>> files in jffs2, >>> >>> 1. cp /etc/* /mnt/mtd/etc/ =A0 =A0(/mnt/mtd is my jffs2 fs) >>> 2. rm -rf /etc/* >>> 3. make symbolic links from all /etc/xx to /mnt/mtd/etc/xxx >>> 4. remake ramdisk rootfs >>> >>> It seems all files in ramdisk rootfs /etc all links to /mnt/mtd/etc/ >>> and try to modify these files is effective after reboot. >>> But is this a common way in embedded linux ? >> Thanks, I understand. >> In principle, but it is easier (and cleaner) to make a symbolic link fro= m >> (say) /etc -> /mnt/mtd/etc without linking every individual file and >> directory. > > i totally agree with ricard when you want to move the entire directory > to jffs2 and not only some selected files > >> You could also use a jffs2 file system in flash for your rootfs, that wa= y >> you wouldn't need a ramdisk at all. > > i'd also recommend you to consider if you really need the > ramdisk. when using a ram disk its entire content is loaded to the RAM > occupying space, even if you don't use certain files (or part of > them). other filesystems are more efficient in this aspect. > if the main purpose is to have a read only rootfs, i'd suggest a look > at squashfs. I consider to use ramdisk as rootfs because worry about wrong operation in rootfs (is use jffs2 rootfs) and it will cause system boot up failed. Another query, does the syslogd/klogd log files also store in jffs2 rootfs? Write to jffs2 frequently will reduce flash life cycle. BRs, H. Johnny > > -- > Matthias Kaehlcke > Embedded Linux Developer > Barcelona > > =A0 =A0 =A0 =A0 =A0 =A0 =A0La posibilidad de realizar un suenyo es lo > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 que hace que la vida sea interesante > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 .''`. > =A0 =A0using free software / Debian GNU/Linux | http://debian.org =A0: :'= =A0: > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0`. `'` > gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0`- >