Why initrd is not needed when manually comp. kernel

scronkey · n00b Joined: 19 Jan 2004 Posts: 31

Hi

Can someone please explain the reason why initrd is not needed
when the kernel is compiled manually? :?:

When using genkernel, an initrd image is created and placed in /boot, and with
my Redhat setup, it also uses initrd, but when using menuconfig, it is not needed.

Why is this?

-scronKey

Voltago · Posted: Tue Jan 20, 2004 12:58 pm Post subject:

Well, in initrd you put everything the kernel has to know about _before_ it mounts your root partition.
Imagine you want to create a distribution, and you don't want to tell the end-user which filesystem he has to use, and you don't know wether he will boot from usb, scsi or [s]ata. So you could compile every necessary driver into the kernel, which would get quite bloated. To avoid this, you put said drivers into a virtual disk (yes, you already guessed, that's initrd), which in fact is 'given' to the kernel by your bootloader, so the kernel can read it with a rather generic fs driver ('initrd support' in kernel config) and without any hardware drivers.
But when you build your own kernel, in contrast, you already know which filesystem you use on your root disk and what your boot device is, so you can compile these drivers into your kernel and forget about initrd.
Just a side note: When you want to use bootsplash (a fancy boot-up screen with progress bar), you'll need initrd again.
Bye!

scronkey · n00b Joined: 19 Jan 2004 Posts: 31

Thanks, great answer!

gonzalo · Posted: Tue Jan 20, 2004 2:06 pm Post subject:

indeed, precise.

ett_gramse_nap · Posted: Tue Jan 20, 2004 3:38 pm Post subject:

Thanks! I've been looking for something like this for a long time...
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