From: Johnny Hung <johnny.hacking@gmail•com>
To: chris@2net•co.uk
Cc: Ricard Wanderlof <ricard.wanderlof@axis•com>,
"linux-embedded@vger•kernel.org" <linux-embedded@vger•kernel.org>,
Marco Stornelli <marco.stornelli@gmail•com>,
kernelnewbies <kernelnewbies@nl•linux.org>,
"linux-mtd@lists•infradead.org" <linux-mtd@lists•infradead.org>,
Matthias Kaehlcke <matthias@kaehlcke•net>,
"linuxppc-dev@lists•ozlabs.org" <linuxppc-dev@lists•ozlabs.org>
Subject: Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
Date: Mon, 25 Jan 2010 16:43:23 +0800 [thread overview]
Message-ID: <cb9ecdfa1001250043q36ecfcack9ea1bb855b538dbf@mail.gmail.com> (raw)
In-Reply-To: <4B5D560E.2020901@2net.co.uk>
2010/1/25 Chris Simmonds <chris@2net•co.uk>:
> Johnny Hung wrote:
>>
>> 2010/1/22 Marco Stornelli <marco.stornelli@gmail•com>:
>>>
>>> 2010/1/22 Johnny Hung <johnny.hacking@gmail•com>:
>>>>
>>>> 2010/1/20 Marco Stornelli <marco.stornelli@gmail•com>:
>>>>>
>>>>> 2010/1/20 Johnny Hung <johnny.hacking@gmail•com>:
>>>>>>
>>>>>> 2010/1/19 Matthias Kaehlcke <matthias@kaehlcke•net>:
>>>>>>>
>>>>>>> El Tue, Jan 19, 2010 at 02:17:22PM +0100 Ricard Wanderlof ha dit:
>>>>>>>
>>>>>> 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
>>>>>>>
>>>>>>> --
>>>>
>>>> It seems there are a lot of file-systems I have to study :P. The same
>>>> 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 rootfs
>> /, I need to add "/dev/mtdblock5 =A0/etc =A0 =A0 =A0 =A0jffs2 =A0 defaul=
ts
>> 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 system =
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 over =
the
> top of the /etc that is in the rootfs, so giving you the read/write versi=
on
> of /etc. Any files open in the old /etc - e.g. /etc/inittab - will contin=
ue
> to be open, but any new files opened in /etc will use the read/write vers=
ion
> in jffs2. You can also do some interesting things with symbolic links...
> 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.uk/
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-embedded"=
in
> the body of a message to majordomo@vger•kernel.org
> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html
>
prev parent reply other threads:[~2010-01-25 8:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-19 9:20 mount ramdisk rootfs /etc directory to jffs2 filesystem Johnny Hung
2010-01-19 9:50 ` Matthias Kaehlcke
2010-01-19 10:13 ` Johnny Hung
2010-01-19 10:20 ` Matthias Kaehlcke
2010-01-19 12:03 ` Johnny Hung
2010-01-19 13:17 ` Ricard Wanderlof
2010-01-19 14:06 ` Matthias Kaehlcke
2010-01-20 2:32 ` Johnny Hung
2010-01-20 7:12 ` Matthias Kaehlcke
2010-01-20 7:15 ` Ricard Wanderlof
2010-01-20 7:17 ` Matthias Kaehlcke
2010-01-22 3:01 ` Johnny Hung
2010-01-20 7:57 ` Marco Stornelli
2010-01-20 10:21 ` Matthias Kaehlcke
2010-01-20 11:54 ` Marco Stornelli
2010-01-22 3:07 ` Johnny Hung
2010-01-22 8:14 ` Marco Stornelli
2010-01-25 4:09 ` Johnny Hung
2010-01-25 8:27 ` Chris Simmonds
2010-01-25 8:43 ` Johnny Hung [this message]
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