Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
Johnny Hung wrote: 2010/1/22 Marco Stornelli marco.storne...@gmail.com: 2010/1/22 Johnny Hung johnny.hack...@gmail.com: 2010/1/20 Marco Stornelli marco.storne...@gmail.com: 2010/1/20 Johnny Hung johnny.hack...@gmail.com: 2010/1/19 Matthias Kaehlcke matth...@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 /etcjffs2 defaults 0 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 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 version of /etc. Any files open in the old /etc - e.g. /etc/inittab - will continue 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... This technique works. I have used it in several projects. -- Chris Simmonds 2net Limited ch...@2net.co.uk http://www.2net.co.uk/ -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/25 Chris Simmonds ch...@2net.co.uk: Johnny Hung wrote: 2010/1/22 Marco Stornelli marco.storne...@gmail.com: 2010/1/22 Johnny Hung johnny.hack...@gmail.com: 2010/1/20 Marco Stornelli marco.storne...@gmail.com: 2010/1/20 Johnny Hung johnny.hack...@gmail.com: 2010/1/19 Matthias Kaehlcke matth...@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 /etc jffs2 defaults 0 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 version of /etc. Any files open in the old /etc - e.g. /etc/inittab - will continue 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... This technique works. I have used it in several projects. -- Chris Simmonds 2net Limited ch...@2net.co.uk http://www.2net.co.uk/ -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/20 Ricard Wanderlof ricard.wander...@axis.com: On Wed, 20 Jan 2010, Johnny Hung wrote: 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. You have a point, however, you could do two things to help: a) Mount the root file system as read-only. That way you can never write to it, unless you remount it read-write. But you can still reflash that partition if you need to upgrade. b) Register the mtd partition holding the root file system as read-only. This is even more seecure as remounting the file system won't permit writes. However, it also means you can't write to it for upgrading. (I don't think the mtd core permits changing an already registered mtd partition from readonly to writable, but I could be wrong.) Another query, does the syslogd/klogd log files also store in jffs2 rootfs? Write to jffs2 frequently will reduce flash life cycle. I think it is fairly common to have a combination of devices: / (root) is a readonly flash device (mtd partition) /etc is a writable flash device (mtd partition) /tmp and /var are ramdisks (tmpfs), so they are writable, but lost when power is cycled. I think it's a good combination for my board. How do I sepcific the /etc to another mtd part? The busybox init will parse /etc/inittab after setup signal handler and initializes console. I only know to do it is to re-mount etc directory from another mtd to /etc. Is it right? Thank your help. BRs, H. Johnny /Ricard -- Ricard Wolf Wanderlöf ricardw(at)axis.com Axis Communications AB, Lund, Sweden www.axis.com Phone +46 46 272 2016 Fax +46 46 13 61 30 -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/20 Matthias Kaehlcke matth...@kaehlcke.net: El Wed, Jan 20, 2010 at 08:57:44AM +0100 Marco Stornelli ha dit: 2010/1/20 Johnny Hung johnny.hack...@gmail.com: 2010/1/19 Matthias Kaehlcke matth...@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 -- In general a good splitting for rootfs could be: squashfs for rootfs, tmpfs for volatile data (/tmp), ubifs (with a flash partition) for strong permanent data (/etc, ) and pramfs for light permanent data (/var/log, .). if ubifs is a good choice depends on the size of the partition, iirc it has a significant overhead for very small partitions. once using ubi it could be interesting to set up the read-only rootfs partition upon ubi in order to spread the wear out over a maximum of blocks. I don't know the size constraints of Johnny, so it can be useful to use jffs2. Marco -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
mount ramdisk rootfs /etc directory to jffs2 filesystem.
Hi ALL, 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? 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? H. Johnny -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/19 Matthias Kaehlcke matth...@kaehlcke.net: 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. 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. Thank your reply. BRs, H. Johnny for further information i recommend the lecture of http://free-electrons.com/doc/flash-filesystems.pdf depending on your requirements/size of the rootfs partitions UBIFS might be an option to consider -- Matthias Kaehlcke Embedded Linux Developer Barcelona El trabajo es el refugio de los que no tienen nada que hacer (Oscar Wilde) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
El Tue, Jan 19, 2010 at 06:13:07PM +0800 Johnny Hung ha dit: 2010/1/19 Matthias Kaehlcke matth...@kaehlcke.net: 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. 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 the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
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? 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 for further information i recommend the lecture of http://free-electrons.com/doc/flash-filesystems.pdf depending on your requirements/size of the rootfs partitions UBIFS might be an option to consider -- Matthias Kaehlcke Embedded Linux Developer Barcelona El trabajo es el refugio de los que no tienen nada que hacer (Oscar Wilde) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
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 ? 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. You could also use a jffs2 file system in flash for your rootfs, that way you wouldn't need a ramdisk at all. /Ricard -- Ricard Wolf Wanderlöf ricardw(at)axis.com Axis Communications AB, Lund, Swedenwww.axis.com Phone +46 46 272 2016 Fax +46 46 13 61 30 -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
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 ? 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. -- Matthias Kaehlcke Embedded Linux Developer Barcelona La posibilidad de realizar un suenyo es lo que hace que la vida sea interesante .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/19 Matthias Kaehlcke matth...@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 La posibilidad de realizar un suenyo es lo que hace que la vida sea interesante .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
On Wed, 20 Jan 2010, Johnny Hung wrote: 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. You have a point, however, you could do two things to help: a) Mount the root file system as read-only. That way you can never write to it, unless you remount it read-write. But you can still reflash that partition if you need to upgrade. b) Register the mtd partition holding the root file system as read-only. This is even more seecure as remounting the file system won't permit writes. However, it also means you can't write to it for upgrading. (I don't think the mtd core permits changing an already registered mtd partition from readonly to writable, but I could be wrong.) Another query, does the syslogd/klogd log files also store in jffs2 rootfs? Write to jffs2 frequently will reduce flash life cycle. I think it is fairly common to have a combination of devices: / (root)is a readonly flash device (mtd partition) /etcis a writable flash device (mtd partition) /tmp and /var are ramdisks (tmpfs), so they are writable, but lost when power is cycled. /Ricard -- Ricard Wolf Wanderlöf ricardw(at)axis.com Axis Communications AB, Lund, Swedenwww.axis.com Phone +46 46 272 2016 Fax +46 46 13 61 30 -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
El Wed, Jan 20, 2010 at 10:32:15AM +0800 Johnny Hung ha dit: 2010/1/19 Matthias Kaehlcke matth...@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. you could set up a rootfs partition with a read-only file system (squashfs, jffs2 mounted ro) and a second partition that's writable. Another query, does the syslogd/klogd log files also store in jffs2 rootfs? Write to jffs2 frequently will reduce flash life cycle. by default the log files will be written to /var/log, if this directory happens to be on a jffs2 partition writes will go there and produce wear out. to avoid this you could set up a small tmpfs (in RAM) and mount it on /var -- Matthias Kaehlcke Embedded Linux Developer Barcelona We can't solve problems by using the same kind of thinking we used when we created them (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 the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
El Wed, Jan 20, 2010 at 08:15:01AM +0100 Ricard Wanderlof ha dit: On Wed, 20 Jan 2010, Johnny Hung wrote: 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. You have a point, however, you could do two things to help: a) Mount the root file system as read-only. That way you can never write to it, unless you remount it read-write. But you can still reflash that partition if you need to upgrade. b) Register the mtd partition holding the root file system as read-only. This is even more seecure as remounting the file system won't permit writes. However, it also means you can't write to it for upgrading. (I don't think the mtd core permits changing an already registered mtd partition from readonly to writable, but I could be wrong.) AFAIK the mtd core doesn't permit changing a partition from ro to rw. but if you happen to need to reflash the partition anyway, you can load a tiny kernel modules that changes the flag indicating if a partition is writable. i once had to recurr to this solution and it works ;) -- Matthias Kaehlcke Embedded Linux Developer Barcelona Tant qu'il y aura sur terre des hommes pour qui existe un concept d' 'honneur national', la menace d'une nouvelle guerre subsistera (B. Traven) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: mount ramdisk rootfs /etc directory to jffs2 filesystem.
2010/1/20 Johnny Hung johnny.hack...@gmail.com: 2010/1/19 Matthias Kaehlcke matth...@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 -- In general a good splitting for rootfs could be: squashfs for rootfs, tmpfs for volatile data (/tmp), ubifs (with a flash partition) for strong permanent data (/etc, ) and pramfs for light permanent data (/var/log, .). I think you should split your rootfs. Ramdisk is an old approach with some drawbacks. Marco -- To unsubscribe from this list: send the line unsubscribe linux-embedded in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
