Because ruisu currently only supports ubuntu 14 04 64bit 3.13.0-24-generic kernel. Therefore, it is necessary to switch the ubuntu kernel to 3.13.0-24-generic kernel. After switching the kernel, there is a problem of login black screen or circular login. Here is a solution reference.

1. View existing kernel versions

root@kongwt-virtual-machine:/home/kongwt/desktop# uname -r
4.4.0-142-generic

2. Install 3.13.0-24-generic kernel file

root@kongwt-virtual-machine:/home/kongwt/desktop# apt-get install linux-image-extra-3.13.0-24-generic

Enter all the way to the end of installation, as follows:

Found linux image: /boot/vmlinuz-4.4.0-142-generic
Found initrd image: /boot/initrd.img-4.4.0-142-generic
Found linux image: /boot/vmlinuz-3.13.0-24-generic
Found initrd image: /boot/initrd.img-3.13.0-24-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
root@kongwt-virtual-machine:/home/kongwt/desktop#

It's best to turn off the virtual machine and turn it on again. Note that turning it off and on again is not a restart, nor is it a return to the virtual machine snapshot. I downloaded the 3.13.0-24-generic kernel file before. Then I was afraid of damaging the system and saving the snapshot in the process of trying. The operation was carried out back to the snapshot, resulting in the failure to solve the black screen phenomenon, So it's best to turn off the virtual machine and turn it on again.

3. Check the existing kernel installed now

root@kongwt-virtual-machine:/home/kongwt/desktop# dpkg -l|grep linux-image
ii  linux-image-3.13.0-24-generic                         3.13.0-24.47                                         amd64        Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-4.4.0-142-generic                         4.4.0-142.168~14.04.1                                amd64        Linux kernel image for version 4.4.0 on 64 bit x86 SMP
ii  linux-image-extra-3.13.0-24-generic                   3.13.0-24.47                                         amd64        Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-extra-4.4.0-142-generic                   4.4.0-142.168~14.04.1                                amd64        Linux kernel extra modules for version 4.4.0 on 64 bit x86 SMP
ii  linux-image-generic-lts-xenial                        4.4.0.142.122                                        amd64        Generic Linux kernel image

4. Uninstall the previous kernel

root@kongwt-virtual-machine:/home/kongwt/desktop# apt-get purge linux-image-4.4.0-142-generic linux-image-extra-4.4.0-142-generic

Press enter all the way. Note that if the latest kernel is not installed on the current server, the latest kernel will be installed on the server at the same time. Therefore, you need to enter the uninstall command again to uninstall the new kernel just installed during the uninstall process. The steps are the same as 3 and 4, as follows:

root@kongwt-virtual-machine:/home/kongwt/desktop# dpkg -l|grep linux-imageii  linux-image-3.13.0-24-generic                         3.13.0-24.47                                         amd64        Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-4.4.0-148-generic                         4.4.0-148.174~14.04.1                                amd64        Signed kernel image generic
ii  linux-image-extra-3.13.0-24-generic                   3.13.0-24.47                                         amd64        Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-generic-lts-xenial                        4.4.0.148.130                                        amd64        Generic Linux kernel image

root@kongwt-virtual-machine:/home/kongwt/desktop# apt-get purge linux-image-4.4.0-148-generic

At this time, look at the existing kernel again:

root@kongwt-virtual-machine:/home/kongwt/desktop# dpkg -l|grep linux-imageii  linux-image-3.13.0-24-generic                         3.13.0-24.47                                         amd64        Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-extra-3.13.0-24-generic                   3.13.0-24.47                                         amd64        Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-unsigned-4.4.0-148-generic                4.4.0-148.174~14.04.1                                amd64        Linux kernel image for version 4.4.0 on 64 bit x86 SMP

If another one is found, continue to uninstall:

root@kongwt-virtual-machine:/home/kongwt/desktop# apt-get purge linux-image-unsigned-4.4.0-148-generic

5. Delete the previous kernel folder
This step is very important. After uninstalling the previous kernel version, I directly restarted without deleting the corresponding prompt folder. Then there were problems such as restart black screen and circular login. I couldn't find many methods, which was a headache.
At the end of step 4, you will be prompted as follows:

Clearing linux-image-unsigned-4.4.0-148-generic (4.4.0-148.174~14.04.1) Configuration file for ...
rmdir: delete "/lib/modules/4.4.0-148-generic" fail: directory not empty

Manually delete the folder of redundant kernel:

root@kongwt-virtual-machine:/home/kongwt/desktop# cd /lib/modules/
root@kongwt-virtual-machine:/lib/modules# ls
3.13.0-24-generic  4.4.0-142-generic  4.4.0-148-generic
root@kongwt-virtual-machine:/lib/modules# rm 4.4.0-142-generic -rf
root@kongwt-virtual-machine:/lib/modules# rm 4.4.0-148-generic -rf

Then restart to enter the normal graphical interface and log in

root@kongwt-virtual-machine:/lib/modules# reboot