Rebuild the official Ubuntu kernel – Ubuntu 16.04 LTS

There are multiple reasons to rebuild the official kernel of a Linux distro but this is not the purpose of this article

just cannot miss the chance to write that all the kernels are built therefore optimized for the very first 64bit Intel/AMD processor! But come on who wants the most important piece of software to be optimized not for his new and expensive processor but for one released 15 years ago???

. Here we are going to show you how to recompile the latest official Ubuntu kernel of Ubuntu 16.04 LTS – the one, which comes with the apt packages system, because this kernel comes with the latest and greatest patches of the Ubuntu team. You should not confuse this howto with the one, which compile a vanilla kernel or the mainline kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/. So if you want a new kernel or the latest from kernel.org this is the right tutorial for Ubuntu – Build your own kernel under Ubuntu using mainline (latest) kernel. The official latest kernel in the Ubuntu repository is not always the latest one from kernel.org, but you can be sure it is probably most secure one, because there are additional modifications, configurations and tests by the team. Here you can see what versions of the kernel are the officials in Ubuntu: https://wiki.ubuntu.com/Kernel/Support

Keep on reading!

Ubuntu 16/18 LTS – load a new kernel without rebooting the server

Here are the commands needed to load a new kernel without rebooting your server or desktop computer. Why you need this? As said in our first article for CentOS 7 – sometime rebooting a server could take 5 to 10 minutes and loading a new kernel is just up to a minute. In fact in most cases loading the new kernel and starting the system then is just under 20-30 seconds, so upgrading your server even with new kernel is super easy lately. We tested it on Ubuntu 16 and Ubuntu 18 servers and it was successful. The system uses systemd and the process is really easy and safe for the systems.

When the processes is initiated the system shutdowns normally (shutting down all running service with systemd) and then load the system immediately with the new kernel and starts the services as usual!

So no need to worry about unflushed data or not proper shutdown of a service! It’s like a normal reboot but without a hardware reboot and is a lot faster!
Here is what is required to load a kernel without hardware rebooting your computer box:

  1. kexec-tools
  2. Load the new kernel, initram file and the command line arguments with “kexec”
  3. Start a systemd target – kexec.target

Ubuntu 16/18 LTS using kexec to load a new kernel

The real commands only for Ubuntu 16/18 LTS:

sudo apt -y install kexec-tools
sudo kexec -l /boot/vmlinuz-4.15.0-33-generic --initrd=/boot/initrd.img-4.15.0-33-generic --command-line="root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro  quiet splash"
sudo systemctl start kexec.target

Here is a real world example with all the output:
And again update your system to see if there is a new kernel and install “kexec-tools”. In our case indeed there is a new kernel – vmlinuz-4.15.0-33-generic

myuser@srv:~$ sudo apt -y upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following package was automatically installed and is no longer required:
  libllvm5.0
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
  amd64-microcode autotools-dev dblatex debhelper dh-strip-nondeterminism docbook-dsssl docbook-utils docbook-xml docbook-xsl fonts-lato fonts-lmodern fonts-texgyre
  intel-microcode iucode-tool jadetex javascript-common kernel-common kernel-package kernel-patch-scripts kernel-wedge kerneloops kerneloops-applet kernelshark kerneltop
  libfile-homedir-perl libfile-stripnondeterminism-perl libfile-which-perl libjs-jquery libllvm6.0 libmail-sendmail-perl libosp5 libostyle1c2 libpotrace0 libptexenc1
  libqpdf21 libruby2.3 libsgmls-perl libsp1c2 libsynctex1 libsys-hostname-long-perl libtexlua52 libtexluajit2 libwebpdemux1 libxml2-utils libzzip-0-13
  linux-headers-4.15.0-33 linux-headers-4.15.0-33-generic linux-image-4.15.0-33-generic linux-modules-4.15.0-33-generic linux-modules-extra-4.15.0-33-generic lmodern lynx
  lynx-common openjade po-debconf preview-latex-style prosper ps2eps python-apt rake ruby ruby-did-you-mean ruby-minitest ruby-net-telnet ruby-power-assert ruby-test-unit
  ruby2.3 rubygems-integration sgml-data sgmlspl sp tex-common tex-gyre texlive texlive-base texlive-bibtex-extra texlive-binaries texlive-extra-utils texlive-font-utils
  texlive-fonts-recommended texlive-fonts-recommended-doc texlive-generic-recommended texlive-latex-base texlive-latex-base-doc texlive-latex-extra
  texlive-latex-extra-doc texlive-latex-recommended texlive-latex-recommended-doc texlive-luatex texlive-math-extra texlive-pictures texlive-pictures-doc texlive-pstricks
  texlive-pstricks-doc tipa trace-cmd xmlto xsltproc
The following packages will be upgraded:
.....
.....
Running mktexlsr /var/lib/texmf ... done.
Building format(s) --all.
        This may take some time... done.
Processing triggers for linux-image-4.15.0-33-generic (4.15.0-33.36~16.04.1) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.15.0-33-generic
/etc/kernel/postinst.d/vboxadd:
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel modules.
/etc/kernel/postinst.d/zz-update-grub:
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.15.0-33-generic
Found initrd image: /boot/initrd.img-4.15.0-33-generic
Found linux image: /boot/vmlinuz-4.13.0-36-generic
Found initrd image: /boot/initrd.img-4.13.0-36-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done

myuser@srv:~$ sudo apt -y install kexec-tools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following package was automatically installed and is no longer required:
  libllvm5.0
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
  kexec-tools
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 77,4 kB of archives.
After this operation, 276 kB of additional disk space will be used.
Get:1 http://bg.archive.ubuntu.com/ubuntu xenial-updates/main amd64 kexec-tools amd64 1:2.0.16-1ubuntu1~16.04.1 [77,4 kB]
Fetched 77,4 kB in 0s (707 kB/s)      
Preconfiguring packages ...
Selecting previously unselected package kexec-tools.
(Reading database ... 253895 files and directories currently installed.)
Preparing to unpack .../kexec-tools_1%3a2.0.16-1ubuntu1~16.04.1_amd64.deb ...
Unpacking kexec-tools (1:2.0.16-1ubuntu1~16.04.1) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for systemd (229-4ubuntu21.4) ...
Processing triggers for ureadahead (0.100.0-19) ...
Setting up kexec-tools (1:2.0.16-1ubuntu1~16.04.1) ...
Generating /etc/default/kexec...
Processing triggers for systemd (229-4ubuntu21.4) ...
Processing triggers for ureadahead (0.100.0-19) ...

     ┌──────────────────────────────────────────────────────────────────┤ Configuring kexec-tools ├───────────────────────────────────────────────────────────────────┐
     │                                                                                                                                                                │ 
     │ If you choose this option, a system reboot will trigger a restart into a kernel loaded by kexec instead of going through the full system boot loader process.  │ 
     │                                                                                                                                                                │ 
     │ Should kexec-tools handle reboots (sysvinit only)?                                                                                                             │ 
     │                                                                                                                                                                │ 
     │                                                 <Yes>                                                    <No>                                                  │ 
     │                                                                                                                                                                │ 
     └────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ 

On the above configuration question mark “” and press Enter.

So we performed an update and there was a new kernel vmlinuz-4.15.0-33-generic, which we would like to load without hardware reboot.
Here is our new kernel in “/boot”

myuser@srv:~$ ls -altr /boot/
total 130420
-rw-r--r--  1 root root   184840 Jan 28  2016 memtest86+_multiboot.bin
-rw-r--r--  1 root root   184380 Jan 28  2016 memtest86+.elf
-rw-r--r--  1 root root   182704 Jan 28  2016 memtest86+.bin
-rw-------  1 root root  3879946 Feb 17  2018 System.map-4.13.0-36-generic
-rw-r--r--  1 root root     2850 Feb 17  2018 retpoline-4.13.0-36-generic
-rw-r--r--  1 root root   213220 Feb 17  2018 config-4.13.0-36-generic
-rw-r--r--  1 root root  1501359 Feb 17  2018 abi-4.13.0-36-generic
-rw-r--r--  1 root root  7710912 May 17 16:50 vmlinuz-4.13.0-36-generic
-rw-------  1 root root  4041375 Aug 16 00:00 System.map-4.15.0-33-generic
-rw-r--r--  1 root root        0 Aug 16 00:00 retpoline-4.15.0-33-generic
-rw-r--r--  1 root root   216913 Aug 16 00:00 config-4.15.0-33-generic
-rw-r--r--  1 root root  1537455 Aug 16 00:00 abi-4.15.0-33-generic
-rw-------  1 root root  8108600 Aug 16 21:58 vmlinuz-4.15.0-33-generic
drwxr-xr-x 24 root root     4096 Sep  7 14:15 ..
-rw-r--r--  1 root root 51290506 Sep  7 14:15 initrd.img-4.13.0-36-generic
-rw-r--r--  1 root root 54451680 Sep  7 14:15 initrd.img-4.15.0-33-generic
drwxr-xr-x  3 root root     4096 Sep  7 14:15 .
drwxr-xr-x  5 root root     4096 Sep  7 14:16 grub

Now we know the kernel and initram file names we just check the kernel arguments in the kernel, load them with kexec and start an systemd target to load the new kernel:

myuser@srv:~$ grep vmlinuz-4.15.0-33-generic /boot/grub/grub.cfg 
        linux   /boot/vmlinuz-4.15.0-33-generic root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro  quiet splash $vt_handoff
                linux   /boot/vmlinuz-4.15.0-33-generic root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro  quiet splash $vt_handoff
                linux   /boot/vmlinuz-4.15.0-33-generic root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro  quiet splash $vt_handoff init=/sbin/upstart
                linux   /boot/vmlinuz-4.15.0-33-generic root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro recovery nomodeset 
myuser@srv:~$ sudo kexec -l /boot/vmlinuz-4.15.0-33-generic --initrd=/boot/initrd.img-4.15.0-33-generic --command-line="root=UUID=061b2936-34bf-4da3-b7d2-b8bde0899f03 ro  quiet splash"
myuser@srv:~$ sudo systemctl start kexec.target
Connection to srv closed by remote host.
Connection to srv closed.

Use the first line of the grep output above (or you can cat the file and see what is in it if you have any doubts) to take the proper kernel boot arguments and do not include anything starting with “$”.

As you can see systemd performs a normal shutdown of all services and targets.

main menu
Normal shutdown

The ssh connection is immediately closed because the reboot is initiated.
After 10-15 seconds our host is alive and the new kernel is loaded successfully:

root@test ~ $ ssh root@srv
root@srv's password: 
Last login: Wed Sep  5 17:15:08 2018 from test
[root@srv ~]# uname -a
Linux srv.local 4.15.0-33-generic #36~16.04.1-Ubuntu SMP Wed Aug 15 17:21:05 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@srv ~]# 

Because we do not wanted to mess up the two output in one article we decided to split it in two separate ones, so here is the previous one for CentOS 7 – “CentOS 7 – load a new kernel without rebooting the CentOS 7 server”

CentOS 7 – load a new kernel without rebooting the server

Here are the commands needed to load a new kernel without rebooting your server or desktop computer. Why you need this? Sometime rebooting a server could take 5 to 10 minutes and loading a new kernel is just up to a minute. In fact in most cases loading the new kernel and starting the system then is just under 20-30 seconds, so upgrading your server even with new kernel is super easy lately. We tested it on CentOS 7 server and it was successful. The system uses systemd and the process is really easy and safe for the systems.

When the processes is initiated the system shutdowns normally (shutting down all running service with systemd) and then load the system immediately with the new kernel and starts the services as usual!

So no need to worry about unflushed data or not proper shutdown of a service! It’s like a normal reboot but without a hardware reboot and is a lot faster!
Here is what is required to load a kernel without hardware rebooting your computer box:

  1. kexec-tools
  2. Load the new kernel, initram file and the command line arguments with “kexec”
  3. Start a systemd target – kexec.target

CentOS 7 using kexec to load a new kernel

The real commands only for CentOS 7:

yum install -y kexec-tools
kexec -l /boot/vmlinuz-3.10.0-862.11.6.el7.x86_64 --initrd=/boot/initramfs-3.10.0-862.11.6.el7.x86_64.img --command-line="root=/dev/mapper/centos_srv-root ro crashkernel=auto rd.lvm.lv=centos_srv/root rd.lvm.lv=centos_srv/swap rhgb quiet LANG=en_US.UTF-8"
systemctl start kexec.target

Here is a real world example with all the output:
As you can see it is important to load the initram file and the exact arguments to the kernel. You should take them from the grub 2 configuration – /boot/grub2/grub.cfg
Here is the real output:

[root@srv ~]# yum -y update
Loaded plugins: fastestmirror
Determining fastest mirrors
 * base: mirrors.neterra.net
 * extras: mirrors.neterra.net
 * updates: mirrors.neterra.net
base                                                                                                                                                 | 3.6 kB  00:00:00     
centos-sclo-rh                                                                                                                                       | 3.0 kB  00:00:00     
centos-sclo-sclo                                                                                                                                     | 2.9 kB  00:00:00     
extras                                                                                                                                               | 3.4 kB  00:00:00     
updates                                                                                                                                              | 3.4 kB  00:00:00     
(1/4): extras/7/x86_64/primary_db                                                                                                                    | 187 kB  00:00:00     
(2/4): updates/7/x86_64/primary_db                                                                                                                   | 5.2 MB  00:00:01     
(3/4): centos-sclo-sclo/x86_64/primary_db                                                                                                            | 292 kB  00:00:01     
(4/4): centos-sclo-rh/x86_64/primary_db                                                                                                              | 3.7 MB  00:00:02     
Resolving Dependencies
--> Running transaction check
---> Package kernel.x86_64 0:3.10.0-862.11.6.el7 will be installed
---> Package kernel-headers.x86_64 0:3.10.0-862.3.2.el7 will be updated
---> Package kernel-headers.x86_64 0:3.10.0-862.11.6.el7 will be an update
---> Package kernel-tools.x86_64 0:3.10.0-862.3.2.el7 will be updated
---> Package kernel-tools.x86_64 0:3.10.0-862.11.6.el7 will be an update
---> Package kernel-tools-libs.x86_64 0:3.10.0-862.3.2.el7 will be updated
---> Package kernel-tools-libs.x86_64 0:3.10.0-862.11.6.el7 will be an update
....
....
[root@srv ~]# yum install -y kexec-tools
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.neterra.net
 * extras: mirrors.neterra.net
 * updates: mirrors.neterra.net
Package kexec-tools-2.0.15-13.el7.x86_64 already installed and latest version
Nothing to do

So we performed an update and there was a new kernel kernel.x86_64 0:3.10.0-862.11.6.el7, which we would like to load without hardware reboot.
Here is our new kernel in “/boot”

[root@srv ~]# ls -altr /boot/
total 171812
-rw-------.  1 root root  3228420 22 Aug  2017 System.map-3.10.0-693.el7.x86_64
-rw-r--r--.  1 root root   140894 22 Aug  2017 config-3.10.0-693.el7.x86_64
-rw-r--r--.  1 root root      166 22 Aug  2017 .vmlinuz-3.10.0-693.el7.x86_64.hmac
-rwxr-xr-x.  1 root root  5877760 22 Aug  2017 vmlinuz-3.10.0-693.el7.x86_64
-rw-r--r--.  1 root root   293027 22 Aug  2017 symvers-3.10.0-693.el7.x86_64.gz
drwxr-xr-x.  3 root root       17 20 Feb  2018 efi
drwxr-xr-x.  2 root root       27 20 Feb  2018 grub
-rw-r--r--.  1 root root   611343 20 Feb  2018 initrd-plymouth.img
-rw-------.  1 root root 51315067 20 Feb  2018 initramfs-0-rescue-cc7889764e86441b8d1eb54e29e81a91.img
-rwxr-xr-x.  1 root root  5877760 20 Feb  2018 vmlinuz-0-rescue-cc7889764e86441b8d1eb54e29e81a91
-rw-------.  1 root root  3409912 21 May 23,50 System.map-3.10.0-862.3.2.el7.x86_64
-rw-r--r--.  1 root root   147823 21 May 23,50 config-3.10.0-862.3.2.el7.x86_64
-rw-r--r--.  1 root root      170 21 May 23,50 .vmlinuz-3.10.0-862.3.2.el7.x86_64.hmac
-rwxr-xr-x.  1 root root  6228832 21 May 23,50 vmlinuz-3.10.0-862.3.2.el7.x86_64
-rw-r--r--.  1 root root   304943 21 May 23,52 symvers-3.10.0-862.3.2.el7.x86_64.gz
dr-xr-xr-x. 17 root root      224 14 Jun  7,18 ..
-rw-------.  1 root root 12997841 14 Jun  7,19 initramfs-3.10.0-693.el7.x86_64kdump.img
-rw-------.  1 root root 20771492 14 Jun  7,20 initramfs-3.10.0-693.el7.x86_64.img
-rw-------.  1 root root 13007444 14 Jun  7,23 initramfs-3.10.0-862.3.2.el7.x86_64kdump.img
-rw-r--r--.  1 root root   147859 14 Aug 22,02 config-3.10.0-862.11.6.el7.x86_64
-rw-------.  1 root root  3414344 14 Aug 22,02 System.map-3.10.0-862.11.6.el7.x86_64
-rw-r--r--.  1 root root      171 14 Aug 22,02 .vmlinuz-3.10.0-862.11.6.el7.x86_64.hmac
-rwxr-xr-x.  1 root root  6242208 14 Aug 22,02 vmlinuz-3.10.0-862.11.6.el7.x86_64
-rw-r--r--.  1 root root   305158 14 Aug 22,05 symvers-3.10.0-862.11.6.el7.x86_64.gz
-rw-------.  1 root root 20774393  5 Sep 15,20 initramfs-3.10.0-862.11.6.el7.x86_64.img
drwx------.  5 root root       97  5 Sep 15,20 grub2
dr-xr-xr-x.  5 root root     4096  5 Sep 15,21 .
-rw-------.  1 root root 20782404  5 Sep 15,21 initramfs-3.10.0-862.3.2.el7.x86_64.img

Now we know the kernel and initram file names we just check the kernel arguments in the kernel, load them with kexec and start an systemd target to load the new kernel:

[root@srv ~]# grep vmlinuz-3.10.0-862.11.6.el7.x86_64 /boot/grub2/grub.cfg 
        linux16 /vmlinuz-3.10.0-862.11.6.el7.x86_64 root=/dev/mapper/centos_srv-root ro crashkernel=auto rd.lvm.lv=centos_srv/root rd.lvm.lv=centos_srv/swap rhgb quiet LANG=en_US.UTF-8
[root@srv ~]# kexec -l /boot/vmlinuz-3.10.0-862.11.6.el7.x86_64 --initrd=/boot/initramfs-3.10.0-862.11.6.el7.x86_64.img --command-line="root=/dev/mapper/centos_srv-root ro crashkernel=auto rd.lvm.lv=centos_srv/root rd.lvm.lv=centos_srv/swap rhgb quiet LANG=en_US.UTF-8"
[root@srv ~]# systemctl start kexec.target
Connection to srv closed by remote host.
Connection to srv closed.

As you can see systemd performs a normal shutdown of all services and targets.

main menu
Normal Shutdown

The ssh connection is immediately closed because the reboot is initiated.
After 10-15 seconds our host is alive and the new kernel is loaded successfully:

root@test ~ $ ssh root@srv
root@srv's password: 
Last login: Wed Sep  5 15:16:08 2018 from test
[root@srv ~]# uname -a
Linux srv.local 3.10.0-862.11.6.el7.x86_64 #1 SMP Tue Aug 14 21:49:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@srv ~]# 

Because we do not wanted to mess up the two output from different linux distros in one article we decided to split it in two separate ones, so here is the one for Ubuntu 16/18 LTS – “Ubuntu 16/18 LTS – load a new kernel without rebooting the server

Missing network interface 10G Intel X520 with error failed to load because of unsupported SFP+

If you have server with 10G Intel X520 network card

05:00.0 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)

and you wonder why your system did not have network and even no interface is shown with the commands

ip addr and ifconfig -a

, it is probably because you used unsupported SFP+ module.
In the “dmesg” you’ll see two line regarding the problem with the interface:

[ 3142.439304 ] ixgbe 0000:05:00.0: failed to load because an unsupported SFP+ or QSFP module type was detected.
[ 3142.439306 ] ixgbe 0000:05:00.0: Reload the driver after installing a supported module.

Only tested modules are supported by default and it’s probably normal there are a great deal of different SFP+ devices and the creators of the kernel driver would not be able to test all the different SFP+ modules in the world, so all tested SFP+ modules work by default and all other not tested need to enable an option in the kernel to instruct the driver to use them!

Enable the unsupported SF+ module of Intel X520. The kernel module name is “ixgbe”:

  • Built-in kernel module, when the ixgbe is build in the kernel, you must pass a configuration parameters to the kernel boot line
    ixgbe.allow_unsupported_sfp=1
    

    Under CentOS 7 and Ubuntu 16/17/18 you can do the following:
    Edit

    /etc/default/grub

    and add at the end of the GRUB_CMDLINE_LINUX the above line. So it should look like:

    GRUB_CMDLINE_LINUX=" ixgbe.allow_unsupported_sfp=1"
    

    And then for CentOS 7 execute:

    grub2-mkconfig -o /boot/grub2/grub.cfg
    

    And for Ubuntu/Debian:

    grub-mkconfig -o /boot/grub/grub.cfg
    

    DO NOT forget to execute a grub2 make configuration command, because the grub2 configuration file must be regenerated to include the option you’ve set.

  • Most linux distros use ixgbe as a kernel module, so they load the module with the initrd image after booting the kernel. We must instruct how the kernel module will be loaded from the initrd image, so the initrd image must be changed. Here is how to do it properly for CentOS 7 and Ubuntu/Debian:
    For the both distros execute the command:

    echo "options ixgbe allow_unsupported_sfp=1" > /etc/modprobe.d/ixgbe.conf
    

    It will create a configuration file for the ixgbe kernel module with the configuration you see between the double quotes. And then reinstall the kernel!!! Because the initrd image will be regenerated. If you do not want to reinstall the current kernel, you must manually regenerate the initrd image.
    Regenerate all the initrd images for the all installed kernels.
    Under CentOS 7:

    dracut --regenerate-all --force
    

    Under Ubuntu/Debian:

    update-initramfs -u -k all
    

How to install the latest linux kernel (mainline) in CentOS 7 distro

Here you can see the steps to install the latest (mainline stable) kernel under CentOS 7, whether we need the latest driver, because we bought a new laptop released for the first time last month with the latest hardware or there is a hot fix of some nasty bug it is of no matter.
Here are the steps about installing the latest kernel to our CentOS 7, you must have root access:

  • STEP 1 Import the public key of the repository, which offer us the packages of the CentOS 7 mainline stable kernel (and some other kernels, like the Red Hat Enterprise Linux (RHEL) 6 and 7 and more, you can check out the site). The site of the repository is

    https://elrepo.org/

    Import the public key

    #change to root user (skip the first line if you are root)
    sudo su
    rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
    
  • STEP 2 Check the latest version of the rpm install package of the repository, the command is under

    To install ELRepo for RHEL-7, SL-7 or CentOS-7:

    So at present the latest version is “7.0-3” and execute to wget to download the package for the repository elrepo:

    wget http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
    
  • STEP 3 Install the elrepo package with yum (you can do it with rpm command, but let yum manage all your packages and metadata for them!)
    yum -y install ./elrepo-release-7.0-3.el7.elrepo.noarch.rpm
    

    STEP 4 List the available kernels from the elrepo to choose the one you like

    yum list available --disablerepo='*' --enablerepo=elrepo-kernel
    

    To install the latest mainline kernel you must use package starting with

    kernel-ml-*

    at moment of writing the latest mainline kernel is

    4.15.4-1.el7.elrepo

    So execute

    yum install -y --enablerepo=elrepo-kernel kernel-ml
    

    And it will pull the

    kernel-ml-4.15.4-1.el7.elrepo.x86_64

    and install it

  • STEP 5 Check if you are going to boot the new kernel, you’ve installed and set the right one to boot

    cat /boot/grub2/grubenv |grep saved
    # GRUB Environment Block
    saved_entry=CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core)
    

    And as you see, no it’ll not boot to the new kernel, so you must configure grub2 to boot your newly just installed kernel. First check all the installed kernels, set the right kernel and then it is mandatory to call

    grub2-mkconfig

    to update the grub2 configuration:

    [root@srv ~]# awk -F\' /^menuentry/{print\$2} /boot/grub2/grub.cfg 
    CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)
    CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core)
    CentOS Linux (0-rescue-0a26fe4b81d845209fb8958c8e29d600) 7 (Core)
    

    The position 0 (YES, it starts from ZERO!) is “CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)”, so you have two options to set it:

    grub2-set-default 0
    grub2-mkconfig -o /boot/grub2/grub.cfg
    

    Check to see if everything is OK with

    [root@srv ~]# cat /boot/grub2/grubenv |grep saved
    saved_entry=0
    

    or you can set the name of the kernel to boot with

    grub2-set-default "CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)"
    grub2-mkconfig -o /boot/grub2/grub.cfg
    

    Check to see if everything is OK with

    [root@srv ~]# cat /boot/grub2/grubenv |grep saved
    saved_entry=CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)
    
  • STEP 6 is just to reboot
    reboot
    

    STEP 4 Verification of running the latest kernel

    root@srv:~# uname -a
    Linux srv.local 4.15.4-1.el7.elrepo.x86_64 #1 SMP Sat Feb 17 13:35:20 EST 2018 x86_64 x86_64 x86_64 GNU/Linux
    

Install log of the procedure (your output may vary depending on your hardware installed in your system):

[root@srv ~]# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
[root@srv ~]# wget http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
--2018-02-19 10:20:42--  http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
Resolving www.elrepo.org (www.elrepo.org)... 69.195.83.87
Connecting to www.elrepo.org (www.elrepo.org)|69.195.83.87|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 8656 (8.5K) [application/x-rpm]
Saving to: ‘elrepo-release-7.0-3.el7.elrepo.noarch.rpm’

100%[=======================================================================>] 8,656       --.-K/s   in 0.001s  

2018-02-19 10:20:42 (6.97 MB/s) - ‘elrepo-release-7.0-3.el7.elrepo.noarch.rpm’ saved [8656/8656]
[root@srv ~]# yum -y install ./elrepo-release-7.0-3.el7.elrepo.noarch.rpm 
Loaded plugins: fastestmirror
Examining ./elrepo-release-7.0-3.el7.elrepo.noarch.rpm: elrepo-release-7.0-3.el7.elrepo.noarch
Marking ./elrepo-release-7.0-3.el7.elrepo.noarch.rpm to be installed
Resolving Dependencies
--> Running transaction check
---> Package elrepo-release.noarch 0:7.0-3.el7.elrepo will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=================================================================================================================
 Package              Arch         Version                   Repository                                     Size
=================================================================================================================
Installing:
 elrepo-release       noarch       7.0-3.el7.elrepo          /elrepo-release-7.0-3.el7.elrepo.noarch       5.2 k

Transaction Summary
=================================================================================================================
Install  1 Package

Total size: 5.2 k
Installed size: 5.2 k
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : elrepo-release-7.0-3.el7.elrepo.noarch                                                        1/1 
  Verifying  : elrepo-release-7.0-3.el7.elrepo.noarch                                                        1/1 

Installed:
  elrepo-release.noarch 0:7.0-3.el7.elrepo                                                                       

Complete!
[root@srv ~]# yum list available --disablerepo='*' --enablerepo=elrepo-kernel
Loaded plugins: fastestmirror                                                                                                                                               
Loading mirror speeds from cached hostfile                                                                                                                                  
 * elrepo-kernel: mirrors.netix.net                                                                                                                                         
Available Packages                                                                                                                                                          
kernel-lt.x86_64                                                                      4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-devel.x86_64                                                                4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-doc.noarch                                                                  4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-headers.x86_64                                                              4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-tools.x86_64                                                                4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-tools-libs.x86_64                                                           4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-lt-tools-libs-devel.x86_64                                                     4.4.116-1.el7.elrepo                                                     elrepo-kernel
kernel-ml.x86_64                                                                      4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-devel.x86_64                                                                4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-doc.noarch                                                                  4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-headers.x86_64                                                              4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-tools.x86_64                                                                4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-tools-libs.x86_64                                                           4.15.4-1.el7.elrepo                                                      elrepo-kernel
kernel-ml-tools-libs-devel.x86_64                                                     4.15.4-1.el7.elrepo                                                      elrepo-kernel
perf.x86_64                                                                           4.15.4-1.el7.elrepo                                                      elrepo-kernel
python-perf.x86_64                                                                    4.15.4-1.el7.elrepo                                                      elrepo-kernel
[root@srv ~]# yum install -y --enablerepo=elrepo-kernel kernel-ml
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: centos.uni-sofia.bg
 * elrepo: mirrors.netix.net
 * elrepo-kernel: mirrors.netix.net
 * extras: centos.uni-sofia.bg
 * updates: centos.uni-sofia.bg
Resolving Dependencies
--> Running transaction check
---> Package kernel-ml.x86_64 0:4.15.4-1.el7.elrepo will be installed
--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================================================================================================
 Package                               Arch                               Version                                           Repository                                 Size
============================================================================================================================================================================
Installing:
 kernel-ml                             x86_64                             4.15.4-1.el7.elrepo                               elrepo-kernel                              44 M

Transaction Summary
============================================================================================================================================================================
Install  1 Package

Total download size: 44 M
Installed size: 195 M
Downloading packages:
kernel-ml-4.15.4-1.el7.elrepo.x86_64.rpm                                                                                                             |  44 MB  00:00:10     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : kernel-ml-4.15.4-1.el7.elrepo.x86_64                                                                                                                     1/1 
  Verifying  : kernel-ml-4.15.4-1.el7.elrepo.x86_64                                                                                                                     1/1 

Installed:
  kernel-ml.x86_64 0:4.15.4-1.el7.elrepo                                                                                                                                    

Complete!
[root@srv ~]# cat /boot/grub2/grubenv |grep saved
# GRUB Environment Block
saved_entry=CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core)
[root@srv ~]# awk -F\' /^menuentry/{print\$2} /etc/grub2.cfg
CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)
CentOS Linux (3.10.0-693.el7.x86_64) 7 (Core)
CentOS Linux (0-rescue-0a26fe4b81d845209fb8958c8e29d600) 7 (Core)
[root@srv ~]# grub2-set-default "CentOS Linux (4.15.4-1.el7.elrepo.x86_64) 7 (Core)"
[root@srv ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.15.4-1.el7.elrepo.x86_64
Found initrd image: /boot/initramfs-4.15.4-1.el7.elrepo.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-693.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-693.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-0a26fe4b81d845209fb8958c8e29d600
Found initrd image: /boot/initramfs-0-rescue-0a26fe4b81d845209fb8958c8e29d600.img
done
[root@srv ~]# reboot
Connection to 192.168.0.18 closed by remote host.
Connection to 192.168.0.18 closed.
...
...
...
[root@srv ~]# uname -a
Linux srv.local 4.15.4-1.el7.elrepo.x86_64 #1 SMP Sat Feb 17 13:35:20 EST 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@srv ~]#

How to install the latest linux kernel (mainline) in Ubuntu (17.10) distro

Sometimes we need to install the latest kernel version of our linux distro (btw it is called “mainline” if you need to google something about it)! Whether we need the latest driver, because we bought a new laptop released for the first time last month with the latest hardware or there is a hot fix of some nasty bug it is of no matter. Here are the steps (and some troubleshooting) about installing the latest kernel to our Ubuntu install 17.10 (with old versions like 16, 15 and 14 should be the same):

  • STEP 1 is to choose our desired kernel from

    http://kernel.ubuntu.com/~kernel-ppa/mainline/

    Open this address in your favorite browser and choose the latest. In our example the latest kernel, which is no release candidate, 4.14.15. Enter the directory

    http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.15.1/

    and choose your build, for example amd64 for your 64bit setup (and for most cases choose -generic- one)

    mkdir /root/latestkernel
    cd /root/latestkernel
    wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.15.1/linux-headers-4.15.1-041501_4.15.1-041501.201802031831_all.deb
    wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.15.1/linux-headers-4.15.1-041501-generic_4.15.1-041501.201802031831_amd64.deb
    wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.15.1/linux-image-4.15.1-041501-generic_4.15.1-041501.201802031831_amd64.deb
    
  • STEP 2 after successfully downloading the 3 files just install them with “dpkg” (the package manager tool)
    sudo dpkg -i linux-headers-4.15.1*.deb linux-image-4.15.1*.deb
    
  • STEP 3 is just to reboot your machine, the installation setup did everything you needed to load this kernel
    reboot
    

    STEP 4 Verification of running the latest kernel

    root@srv:~# uname -a
    Linux srv.local 4.15.1-041501-generic #201802031831 SMP Sat Feb 3 18:32:13 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
    

Install log of the procedure (your output may vary depending on your hardware installed in your system):

root@srv:~/latestkernel# sudo dpkg -i linux-headers-4.15.1*.deb linux-image-4.15.1*.deb
Selecting previously unselected package linux-headers-4.15.1-041501.
(Reading database ... 200430 files and directories currently installed.)
Preparing to unpack linux-headers-4.15.1-041501_4.15.1-041501.201802031831_all.deb ...
Unpacking linux-headers-4.15.1-041501 (4.15.1-041501.201802031831) ...
Selecting previously unselected package linux-headers-4.15.1-041501-generic.
Preparing to unpack linux-headers-4.15.1-041501-generic_4.15.1-041501.201802031831_amd64.deb ...
Unpacking linux-headers-4.15.1-041501-generic (4.15.1-041501.201802031831) ...
Selecting previously unselected package linux-image-4.15.1-041501-generic.
Preparing to unpack linux-image-4.15.1-041501-generic_4.15.1-041501.201802031831_amd64.deb ...
Examining /etc/kernel/preinst.d/
run-parts: executing /etc/kernel/preinst.d/intel-microcode 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic
Done.
Unpacking linux-image-4.15.1-041501-generic (4.15.1-041501.201802031831) ...
Setting up linux-headers-4.15.1-041501 (4.15.1-041501.201802031831) ...
Setting up linux-headers-4.15.1-041501-generic (4.15.1-041501.201802031831) ...                                                                                             
Setting up linux-image-4.15.1-041501-generic (4.15.1-041501.201802031831) ...                                                                                               
Running depmod.                                                                                                                                                             
update-initramfs: deferring update (hook will be called later)                                                                                                              
Examining /etc/kernel/postinst.d.                                                                                                                                           
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic                                                      
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic                                                       
update-initramfs: Generating /boot/initrd.img-4.15.1-041501-generic                                                                                                         
run-parts: executing /etc/kernel/postinst.d/unattended-upgrades 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic                                                   
run-parts: executing /etc/kernel/postinst.d/update-notifier 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic                                                       
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.15.1-041501-generic /boot/vmlinuz-4.15.1-041501-generic                                                        
Generating grub configuration file ...                                                                                                                                      
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.                                                                   
Found linux image: /boot/vmlinuz-4.15.1-041501-generic                                                                                                                      
Found initrd image: /boot/initrd.img-4.15.1-041501-generic                                                                                                                  
Found linux image: /boot/vmlinuz-4.14.15-041415-generic                                                                                                                     
Found initrd image: /boot/initrd.img-4.14.15-041415-generic                                                                                                                 
Found linux image: /boot/vmlinuz-4.13.0-32-generic
Found initrd image: /boot/initrd.img-4.13.0-32-generic
Found linux image: /boot/vmlinuz-4.13.0-21-generic
Found initrd image: /boot/initrd.img-4.13.0-21-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
root@srv:~/latestkernel#

Ryzen Threadripper kernel problems with PCIe – wifi, network, video problems

If you have Ryzen Threadripper (in my case 1950X) and Ubuntu 17.10 (because the others versions do not boot at all!) with the latest kernel 4.15.x and the default vmlinuz-4.13.0-21-generic you might experience frequently wifi, network cards and video cards problems like wifi disconnects and network cards lost connections and some kind of freezes for a second or two of the video! If you have Ryzen Threadripper 1950X and or ASUS ROG ZENITH EXTREME (or any other motherboard with the chipset AMD X399) and ubuntu 17.10 or probably any linux distro with any kernel you might experience really unstable system. Look at your dmesg and if you see something like

[   18.669950] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   18.669966] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   18.669970] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   18.669973] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   18.669975] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   23.805640] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   23.805664] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   23.805669] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   23.805674] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   23.805678] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   23.838698] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   23.838716] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   23.838720] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   23.838725] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   23.838728] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   36.124101] atlantic: link change old 0 new 100
[   36.124222] IPv6: ADDRCONF(NETDEV_CHANGE): enp65s0: link becomes ready
[   52.294413] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   52.294436] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   52.294441] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   52.294446] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   52.294449] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   53.275256] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   53.275289] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   53.275293] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   53.275298] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   53.275301] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   53.418493] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   53.418517] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   53.418522] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   53.418527] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   53.418530] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[   53.649938] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[   53.649962] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[   53.649967] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[   53.649972] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[   53.649975] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[  113.294411] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[  113.294434] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[  113.294439] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[  113.294444] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000040/00006000
[  113.294450] pcieport 0000:00:01.1:    [ 6] Bad TLP               
[  265.469397] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[  265.469419] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[  265.469424] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Transmitter ID)
[  265.469429] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00001000/00006000
[  265.469438] pcieport 0000:00:01.1:    [12] Replay Timer Timeout  
[  533.031982] dpc 0000:00:01.1:pcie010: DPC containment event, status:0x1f00 source:0x0000
[  533.032004] pcieport 0000:00:01.1: AER: Corrected error received: id=0000
[  533.032009] pcieport 0000:00:01.1: PCIe Bus Error: severity=Corrected, type=Data Link Layer, id=0009(Receiver ID)
[  533.032014] pcieport 0000:00:01.1:   device [1022:1453] error status/mask=00000080/00006000
[  533.032022] pcieport 0000:00:01.1:    [ 7] Bad DLLP      

Apparently everything on the pci express could be affected! So till the kernel team fixes the issues, you can use the following workaround: add to the kernel boot parameters

pcie_aspm=off

Under Ubuntu you can add in the file

/etc/default/grub

the following line

GRUB_CMDLINE_LINUX="pcie_aspm=off"

And then execute

update-grub

the changes to take effect in the grub configuration. Then reboot the machine!

Under CentOS 7 the configuration file and the line to put are the same just the update of the grub configuration is different:

  • For UEFI-based systems execute:
    grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
    
  • For legacy-BIOS systems execute:
    grub2-mkconfig -o /boot/grub2/grub.cfg
    

*You should know what is your setup, probably UEFI-based, you could check in your boot directory, if there is /boot/efi/EFI/centos/grub.cfg you probably should use the option for UEFI-based, if you do not have any “efi” directory under “/boot” use the second option for legacy-BIOS.
Then reboot the machine!