mount ramdisk rootfs /etc directory to jffs2 filesystem.

[Johnny Hung]

2010/1/19 Matthias Kaehlcke <matthias at kaehlcke.net>:
> 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/    (/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 from
>> (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 way
>> 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
>
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