I came across the following statement ..

When booting Linux, the boot loader is responsible for loading the kernel image and the initial RAM disk (which contains some critical files and device drivers needed to start the system) into memory.

what does it mean to load a kernal image and initial RAM disk,Is there any command or application by which I can see them logically where they are ?


To "load" them means copying them from the boot medium (harddisk, CD, USB stick, ...) to system RAM.

The CPU can only receive instructions directly from either the BIOS or the RAM; in order to run a program stored on the hard disk, there needs to be a program that is already accessible that will make the other program accessible.

At system start, there is only the BIOS, which knows how to test the RAM for defects and read data from the hard disk. The BIOS loads the bootloader, which is placed so that it can be found easily (either at the beginning of the disk, or in a special partition).

The bootloader is an intermediate program that basically just performs the same function as the BIOS -- it loads the next program. Unlike the BIOS, it is specifically made to load Linux, so it knows how to read the Executable and Linking Format (which is used for programs under Linux), and it knows that it should also read the initrd file into memory and pass the address where its contents can be found to the Linux kernel.

The kernel itself can typically be found in the /boot directory, with a name of vmlinuz- followed by a version number, and at the moment you can execute commands, a copy of it is somewhere in system memory; the exact address is unpredictable.

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  • Thanx Sir it helped me.. but why it is stated kernal as a image file instead of other formats..futhermore in my /root directory I have vimliz and vimliz.old ,initrd.img and initrd.img.old what does that means? – lazarus Aug 29 '14 at 11:34
  • @jazzz, the word image is used in the technical meaning "A file that contains all information needed to produce a live working copy." The files you can find in the root (/) directory are symbolic links pointing to the active and the previously active kernel and initrd files; these are used e.g. when you use the LILO bootloader instead of the Ubuntu default, grub. – Simon Richter Aug 29 '14 at 12:13

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