kernel boot procedure

[SaNtosh kuLkarni]

I guess this is wot u r looking for ..not sure thou..

 initial RAM filesystem is bsasically a ramfs which is loaded by the  boot
loader (loadlin or lilo) and that is mounted as root  before the normal
boot procedure is done and is typically used to  load modules needed to
mount the original root file system,[[[Documentation/initrd.txt]]]]

If BLK_DEV_RAM is also included it also enables initial RAM disk (initrd)
support and adds 15 Kbytes (more on some other architectures) to the kernel
size.

On Sun, Mar 4, 2012 at 3:15 AM, Manavendra Nath Manav
<mnm.kernel at gmail.com>wrote:

> On Sun, Mar 4, 2012 at 2:46 AM, beyond.hack <beyond.hack at gmail.com> wrote:
> > ***        when bootloader in bios executes its code, it do POST and
> other
> > things...then as I read from somewhere  kernel does initrd to load some
> > basic modules so as to mount the root file system and then removes the
> > initrd fs.....
> > (srry my mistake)
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> >
>
> Quoting from Understanding the Linux Kernel:
>
> The LILO boot loader is too large to fit into a single sector, thus it
> is broken into two parts. The
> MBR or the partition boot sector includes a small boot loader, which
> is loaded into RAM starting from
> address 0x00007c00 by the BIOS. This small program moves itself to the
> address 0x00096a00, sets up
> the Real Mode stack (ranging from 0x00098000 to 0x000969ff), loads the
> second part of the LILO boot
> loader into RAM starting from address 0x00096c00, and jumps into it.
>
> The LILO boot loader, which relies on BIOS routines, performs
> essentially the following operations:
> 1. Invokes a BIOS procedure to display a "Loading" message.
> 2. Invokes a BIOS procedure to load an initial portion of the kernel
> image from disk: the first 512 bytes of the kernel image are put in
> RAM at address 0x00090000, while the code of the setup( ) function is
> put in RAM starting from address 0x00090200.
> 3. Invokes a BIOS procedure to load the rest of the kernel image from
> disk and puts the image in RAM starting from either low address
> 0x00010000 (for small kernel images compiled with make zImage) or high
> address 0x00100000 (for big kernel images compiled with make bzImage).
> We say that the kernel image is "loaded low" or "loaded high" in RAM,
> respectively.
> 4. Jumps to the setup( ) code.
>
> So, you see the init routine is run only after the kernel has been
> loaded in RAM.
>
> --
> Manavendra Nath Manav
>
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