Hi,

I'm new Linux user and I'm searching for help.

I'm trying to speed up booting time on my Dell Latitude 6220. I've found out that I can bypass grub bootloader using the kernels built in efistub loader.

I've found tutorial for ubuntu here but modified it to work on deepin with mixed results.

This is what I have done:

1. Created 3 partitions using gparted from live cd.
sda1 - efi (500mb)
sda2 - /
sda3 - home

2. Installed deepin on sda2 and pointed the efi and home partition. (system boots but using grub)

3. Created /etc/kernel/postinst.d/zz-update-efistub with the following contents:

#!/bin/sh
cp /vmlinuz /initrd.img /boot/efi/EFI/deep/

4. Then made executable with parameters:

sudo chmod +x /etc/kernel/postinst.d/zz-update-efistub
sudo /etc/kernel/postinst.d/zz-update-efistub

and i run it.

5. Added boot entry:

sudo efibootmgr -c -d /dev/sda -p 1 -L "Deepin (efistub)" -l /EFI/deep/vmlinuz -u "root=/dev/sda2 rw initrd=/EFI/deep/initrd.img quiet splash"

And now the pc boots from the kernel but gives an error: "vfs: unable to mount root fs on unknown block"

As I understand kernel cannot mount the root partition or as I found on the net it cannot find the initrd.img to point it to the root.

I've heard that I can hardcode the root path into the kernel but that's above my abilities.

And to my question.. Does anybody have an idea how to successfuly boot the deepin using efistub loader?

Hello, welcome to LQ.

Instructions below are valid for any Linux distribution, I think.

You need to rebuild your kernel with specific configure options:
CONFIG_BLK_DEV_INITRD=y
To be able to use an initrd
CONFIG_INITRAMFS_SOURCE=<path to your initrd>
The initrd should be a cpio archive, i.e. not gzipped (making the kernel will compress it).
CONFIG_EFI_STUB=y
This kernel feature allows a bzImage to be loaded directly by EFI firmware without the use of an external boot loader.
CONFIG_CMDLINE_BOOL=y
Allow for specifying boot arguments to the kernel at build time.
CONFIG_CMDLINE=<your boot command line>
Enter arguments here that should be compiled into the kernel image and used at boot time.
This is should be the same command line as if you used a boot manager, minus the indication of the kernel and the initrd but indicating of course the root device.

So basically that makes a bundle of the kernel including the EFI loader and the initrd, with a built-in command line.

EDIT: I almost forgot: you will need to have the kernel renamed BOOTX64.EFI and located in /EFI/BOOT/ in the iso so that the EFI firmware finds it.

Only caveat: you won't be able to edit the command line at boot time. Changing it will need to rebuild the kernel.


Best regards,