From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johnny Hung Subject: Re: mount ramdisk rootfs /etc directory to jffs2 filesystem. Date: Mon, 25 Jan 2010 16:43:23 +0800 Message-ID: References: <20100119140600.GH16182@darwin> <2ea1731b1001192357r72d627e2gb36d71f23fd69b2e@mail.gmail.com> <2ea1731b1001220014v59ea7767m6e1a8547d41c6afb@mail.gmail.com> <4B5D560E.2020901@2net.co.uk> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=yUvsYjDMxqEoJ2VyV9/80MG5uFbSAlHfWHZfAGZtWps=; b=RNS8EdV04Go0bx1t1y4Ejw2lbKh/zcm/LrT61H1xFSB0PY1oCKW3yCHu0yPPblZb+E kyz1DF0mBIWLhr24J6QBMnuvdzOL4M7EjL+drzeA84TihWtMefQf9uu4qeqYeR5CeMHX GBdrJIyZUIHVORT8dOngDELSWknQZhRqHse34= In-Reply-To: <4B5D560E.2020901@2net.co.uk> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: chris@2net.co.uk Cc: Marco Stornelli , Matthias Kaehlcke , Ricard Wanderlof , kernelnewbies , "linux-mtd@lists.infradead.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-embedded@vger.kernel.org" 2010/1/25 Chris Simmonds : > Johnny Hung wrote: >> >> 2010/1/22 Marco Stornelli : >>> >>> 2010/1/22 Johnny Hung : >>>> >>>> 2010/1/20 Marco Stornelli : >>>>> >>>>> 2010/1/20 Johnny Hung : >>>>>> >>>>>> 2010/1/19 Matthias Kaehlcke : >>>>>>> >>>>>>> El Tue, Jan 19, 2010 at 02:17:22PM +0100 Ricard Wanderlof ha di= t: >>>>>>> >>>>>> I consider to use ramdisk as rootfs because worry about wrong >>>>>> operation in rootfs (is use jffs2 rootfs) and it will cause syst= em >>>>>> boot up failed. >>>>>> Another query, does the syslogd/klogd log files also store in jf= fs2 >>>>>> rootfs? Write to jffs2 frequently will reduce flash life cycle. >>>>>> >>>>>> BRs, H. Johnny >>>>>>> >>>>>>> -- >>>> >>>> It seems there are a lot of file-systems I have to study :P. The s= ame >>>> question is >>>> how to split my rootfs? Re-mount /etc, /var to another file-sysyem= mtd >>>> part when >>>> system boot up? >>>> >> Yes, I know. So if I want set etc directoyr to /dev/mtd5 not in root= fs >> /, I need to add "/dev/mtdblock5 =A0/etc =A0 =A0 =A0 =A0jffs2 =A0 de= faults >> 0 =A0 =A0 =A0 0" in /etc/fstab file but rootfs doesn't contain /etc >> directory because /etc directoyr is store in /dev/mtdblock5. >> Do you know what I mean? The kernel execute /sbin/init after mount >> rootfs and /sbin/init is link to busybox, busybox will read >> /etc/inittab file to initial. The problem is coming, how busybox to >> read /etc in rootfs before mount /dev/mtdblock5 to /etc? There is no >> program to mount /dev/mtdblock5 to /etc before busybox init execute. >> >> I think I must mistake some concept, please give me a hint. >> Thank you >> BRs, H. Johnny >> > I got it. The rootfs contains at least /etc directory, /etc/inittab, /etc/fstab. Bysybox will read /etc/fstab to mount etc to rootfs's etc from other partition. Okay, it's reasonable. Another query, how to do it in many Linux dist as Macro mentioned, use initramfs ? I am sure I can arrange / to /dev/hda1 and /etc to /dev/hda2. Thank you so much BRs, H. Johnny > You have two /etc directories: one in the the read-only root file sys= tem and > one in the jffs2 fs. In the root fs you have /etc/fstab, /etc/inittab= and > any scripts it may call. The init program will mount /dev/mtdblock5 o= ver the > top of the /etc that is in the rootfs, so giving you the read/write v= ersion > of /etc. Any files open in the old /etc - e.g. /etc/inittab - will co= ntinue > to be open, but any new files opened in /etc will use the read/write = version > in jffs2. You can also do some interesting things with symbolic links= =2E.. > This technique works. I have used it in several projects. > > -- > Chris Simmonds =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 2net Limited > chris@2net.co.uk =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 http://www.2net.co.u= k/ > > -- > To unsubscribe from this list: send the line "unsubscribe linux-embed= ded" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html >