2010/1/20 Ricard Wanderlof <ricard.wanderlof@xxxxxxxx>: > > 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 an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
