Friday, April 16, 2021

Cent OS 8 is not booting with the latest Kernel

 CentOS 8 is not booting with the latest kernel


I have installed Centos 8 operating system and it has updated with the installation. There were three kernels listed in the /boot folder 4.8.1, 4.8.10 and 4.8.22. After completing all the installation I have rebooted the server to boot with latest kernel version. Yet, it was found that the server was booted with 4.8.10 kernel not with the latest. Even grub does not show the 4.8.22 kernel to select and boot. 

To ensure the what is the default kernel which shows by the OS, run the several commands and ensure the default kernel set to the latest.

# rpm -qa | grep kernel | sort

# grubby --info=ALL | grep ^kernel

# grubby --grub2 --default-title ( It shows that default booting kernel is 4.8.22 even though it has not booted)

# grubby --default-kernel

Above commands set confirm that default kernel is set to the latest (4.8.22). Unfortunately, there were no any error logs related to the issue. I have searched through the google to find out a solution, but most of the google results did not provide a correct solution. 

Fortunately while going through deep search I was able find one clue stating that there was a issue with 4.8.22 kernel for several servers. It was a simple solution to address this issue which is reinstall the grub again. As this is test server without having second thought I have reinstalled the grub with the below command.

dnf reinstall grub*

The reboot solve everything after that. 

Further reading:     https://forums.centos.org/viewtopic.php?t=77412&p=325535     

                               https://www.golinuxcloud.com/change-default-kernel-version-rhel-centos-8/

Thursday, April 15, 2021

Arch Linux Sound Drive not detected

 Arch Linux Sound Drive not detected

 

I have bought a Dell Vostro 3000 series laptop. It was designed for the business use. Even though I have installed the Arch Linux for many different hardware platform, this is the first time I have encountered a problem with sound driver. Usually arch linux does not have issues with hardware drivers. It all configured properly with the installation. 

 I have tried several ways to rectify the sound driver issue. Even i have installed the alsa software as well. But the real solution was to disable the  dmic since it was issues with the Linux kernel version 5.5 and above. Earlier version of Linux kernel explicitly disable the dmic. 

 

Add new file in the modprobe to disable the kernel version.

/etc/modprobe.d/disable_dmic.conf 

options snd_hda_intel dmic_detect=0 

 Then reboot the Arch Linux machine. Below are the supporting links. 

https://bbs.archlinux.org/viewtopic.php?pid=1887925#p1887925

https://bbs.archlinux.org/viewtopic.php?pid=1888046#p1888046


If you need further reading about Arch Linux sound driver behavior below is a good reading.

https://wiki.archlinux.org/index.php/Advanced_Linux_Sound_Architecture/Troubleshooting#No_output