In message <528646bc05021202175e967842 at mail.gmail.com> you wrote: > > > There will be parameters of about 65KB are to be used and these parameters > > can be changed in the field. This parameter block will have 2 copies to > > avoid data corruption due to power fail. Hence to avoid the use of NAND > > Flash I will be using 2 Parameter files to read and write(into flash) in a > > linux environment during normal operation. Am I right?? > You could map the FLASH as a MTD device and write to two different > sectors directly; then you can use a RAM disk instead of going with > JFFS on your flash. Use a separate RedBoot partition for each > parameter sector. (Note; using RedBoot partitions does not preclude > using u-boot)
I can't parse that. Using a ramdisk (as root filesystem?) has nothing to do with using a JFFS2 (not JFFS) filesystem for data storage. And actually it's usually better to use a cramfs based root filesystem plus tmpfs for transient data storage. Finally, I don't see any reason for a "RedBoot" partition - any MTD partition will work just fine. > > In this mailing list I have read the typical size of U-BOOT will be around > > 256KB as suggested by Wolfgang Denk. > U-boot will live at the beginning of flash. The u-boot environment > will take up another sector. Your parameter files will take up at This is not correct. U-Boot is located where your memory map dictates it, this can be the begining or the end or right in the middle of your flash - depending on your hardware design. And 256 kB is an upper size limit including the environment (with enough spare even for redundand environment in most configuration). A typical U-Boot image (including environment) is 150...190 kB. > least one sector each. The rest can be dedicated to the kernel and > initrd images. Set up a RedBoot partition for each. What for? > How much RAM does your app need? 32M is gobs for a simple system. If > it's ultra simple you may even be able to go down to 16 (don't quote In 16 MB you can run a native GCC which definitely is far beyond being "ultra simple". > me though). Add more if your app is RAM hungry. 16M of flash should > also be gobs. (Assuming 1-2M for the kernel and the rest for the > initrd image) It is very difficult to make recommendations without more information about system requirements. Yes, it is usually possible to implement simple devices like a firewall / router / WLAN AP etc. in 4 or better 8 MB flash and 16 MB RAM. But you will also have to take into account if there are requirements like reliable software updates with guaranteed fall-back (which may require storage capacity for the fall-back version) or similar features. Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de "If you own a machine, you are in turn owned by it, and spend your time serving it..." - Marion Zimmer Bradley, _The Forbidden Tower_
