Hi Mandeep, Thank you for sharing your points and links. Appreciated your help.
On Mon, Oct 18, 2010 at 10:27 PM, Mandeep Sandhu < [email protected]> wrote: > > I have very little knowledge on how to create ramdisk. I don;t know much > > about rootdisk mean. Also, which one of these two is loaded first, when > > booting up a network system/device etc. > > I'm not sure what rootdisk means, but i guess it's the disk > (hard-disk/flash etc) where your root directory lives. > > ramdisk on the other hand is a filesystem image that can be loaded on > to the RAM. It emulates a block device in RAM and uses it as a backing > store for a regular FS. The regular FS's support must be built into > the kernel. > > ramdisk is loaded first. > > > > > what are the contents goes to ramdisk & rootdisk?. Basically. I am > looking > > ramdisk image basically contains driver modules and other essential > utilities which help the kernel load your actual root FS (aka > rootdisk). > > Eg: if your root FS is on a SATA drive, then the kernel would need the > SATA driver for talking to the drive. It would also need the relevant > FS module (ext/ext3 etc) for reading/writing to the FS image on the > SATA drive. These modules will packaged as part of your ramdisk image. > > I "think", initramdisk/initrd images have been superseded by the more > popular initramfs nowadays (not completely sure though). > > "initramfs" does not require any FS support in the kernel. It is much > simpler than a "ram disk" image since it does not have to deal with > writing to backing store (which the ram disk was emulating), managing > buffers etc. Rather its not a FS at all, but a CPIO archive which is > unpacked by the kernel in ram and then accessed w/o the need of a FS. > > You can read more here: > > http://www.mjmwired.net/kernel/Documentation/filesystems/ramfs-rootfs-initramfs.txt > > > > for more information how to start a devices with these two. > > Is it possible to boot a device with ramdisk alone? > > Yes its possible, provided your ramdisk has the relevant bits. > Eg a lot of embedded systems boot a ramdisk image with busybox in it. > > HTH, > -mandeep > > > > > > Thanks in advance. > > > > Regards, > > SS. > > > -- Regards, S. Sengottuvelan.
