2010/1/19 Matthias Kaehlcke <matthias@xxxxxxxxxxxx>: > El Tue, Jan 19, 2010 at 06:13:07PM +0800 Johnny Hung ha dit: > >> 2010/1/19 Matthias Kaehlcke <matthias@xxxxxxxxxxxx>: >> > El Tue, Jan 19, 2010 at 05:20:53PM +0800 Johnny Hung ha dit: >> > >> >> I have build an embedded Linux system and rootfs is a ramdisk. Ramdisk >> >> rootfs resides in memory so modify files is non-effective after a >> >> reboot. Some directories in rootfs, like /etc, /usr, ... are contain >> >> many application configuration files and I want to mount it to jffs2 >> >> flash filesysyem so it will take effect after a reboot. Is it >> >> possible? >> > >> How to do it? The ramdisk rootfs is ext2 filesystem and I try, >> mount /mnt/mtd/etc /etc >> >> Try to modify /etc/ files is not works. > > ok, i understood you want to substitute the ramdisk rootfs by jffs2 > based one > > mounting the ramdisk as writable with the flash as backing storage > isn't possible AFAIK. and even if it was possible it wouldn't be > recommended as ext2 doesn't care about flash wear out, in consequence > you would write the same blocks over and over again. > >> > yes, this is possible >> > >> >> I know the flash has write times limited so the log files >> >> (syslogd/klogd) should not store in flash. In general, how to deploy >> >> root file system for embedded linux with flash storage? >> > >> > - add jffs2 support to your kernel >> > - create your image using mkfs.jffs2 from mtd-utils >> > - flash the image >> > - specify the rootfs partition and type in the bootargs of the kernel >> The above procedure is to create a jffs2 rootfs image but I prefer to >> use ramdisk rootfs. >> I think the rootfs is build as ramdisk and some configurable file is >> store in jffs2 flash. > 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 ? I also have another idea, keep ramdisk rootfs /etc files and add a shell script. 1. The shell script execute when system boot up. 2. Check /mnt/mtd/etc/xxx if is exist. If yes, remove /etc/xxx file and make a symbolic link to /mnt/mtd/etc/xxx. If no, keep /etc/xxx file. 3. repeat 2 for all /etc files Any suggestion? Thank your help. BRs, H. Johnny > in this case follow the above steps, except the last one about the > bootargs and mount the jffs2 partition from your init script. you > could use symlinks from your ramdisk to the files on jffs2 to > integrate them in your rootfs > > -- > Matthias Kaehlcke > Embedded Linux Developer > Barcelona > > Anyone who has never made a mistake has never tried anything new > (Albert Einstein) > .''`. > using free software / Debian GNU/Linux | http://debian.org : :' : > `. `'` > gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
