Boot stucks at "Loading initial ramdisk"

[Aditya Gupta]

Hi Dileep,

On Mon, Jan 01, 2024 at 04:46:03PM +0530, Dileep Sankhla wrote:
> >
> > Thanks for your solution. Mine is fine in size and I am already using
> > MODULES=dep.
> >
> 
> Sorry, my bad. I thought 18M was good enough but after asking this on
> LinuxQuestions.org, I got to know that it was not sufficient for the boot
> success (see [1]). Copying the existing kernel version's config from
> `/boot` and running `make olddefconfig` solved the size issue for me. It is
> now ~78M. The size of the kernel's initrd that I was using earlier is ~71M.
> 

Just for the clarity, the size of initrd being only 18 MB is likely not
the root cause for your system not booting, it would likely be that some
modules were missing earlier.

Likely why you built linux with a default config (defconfig), many
modules might have been missing, which are required on your system to
boot correctly. For example, file system support for btrfs will require
the btrfs module, etc.

Generally while creating initrd, `dracut` (on rhel/fedora), or
`mkinitcpio`/`mkinitramfs` also copy your kernel's modules (at
/lib/modules/new-kernel-version/*) to the initrd.

Since you had less modules the first time you built with defconfig, so
initrd also had less modules, and hence size was only 18MB.

Later when you built using the distro kernel's config, you likely had
many more modules, and hence more modules were put in the initrd also,
causing it's size to increase, and since you used distro kernel config,
so your modules would be similar in the kernel you built, and hence
similar size of the initrd ~70MB.

It's a good start to use the distro config for building a kernel.

PS. I have been able to successfully boot by building with defconfig,
then manually enabling some drivers according to error messages during
boot, but that is for learning only, normally it might be a waste of
time.
And also I boot my ArchLinux with no initrd, and have had even smaller
initrd and booted successfully, how I did that was building only the
modules I knew my system needed as built-in.

Regards,
Aditya Gupta