Compiling and Upgrading the VM Kernel to 4.x on Alibaba Cloud ECS

Today, I tested upgrading the CentOS 7.x kernel from version 3.x to 4.x by compiling it manually. Here is a record of the process. Previously, Alibaba Cloud ECS did not support kernel upgrades. In fact, Alibaba Cloud systems running CentOS 5.8 or later already support kernel upgrades via yum. However, upgrading the kernel is a risky operation, especially in cloud environments with customized non-standard hardware. Therefore, the Alibaba Cloud ECS Purchase Notes explicitly warn against casually upgrading the kernel.

Operations carry risks; please ensure you have taken snapshot backups. Below is the operational procedure:

Check the current system version: CentOS 7.0; Kernel version: 3.10.0;

[root@iZ28yx1yevuZ ~]# lsb_release -a
LSB Version:    :core-4.1-amd64:core-4.1-noarch
Distributor ID: CentOS
Description:    CentOS Linux release 7.0.1406 (Core)
Release:        7.0.1406
Codename:       Core
[root@iZ28yx1yevuZ ~]# uname -r
3.10.0-123.9.3.el7.x86_64

Go to kernel.org to download the latest kernel version:

[root@iZ28yx1yevuZ ~]#wget https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.1.6.tar.xz;mv linux-4.1.6.tar.xz /usr/src
[root@iZ28yx1yevuZ ~]#cd /usr/src;tar -xf linux-4.1.6.tar.xz

This is because menuconfig requires ncurses-devel support. Install ncurses-devel and recompile:

root@iZ28yx1yevuZ ~]# yum install ncurses-devel -y

Since most Alibaba Cloud machines are still in a Xen environment, compiling the kernel in this environment requires adding Xen guest support compared to standard systems. See below (if you cannot find the configuration in menuconfig, you can search using “/” like in vi):

Note: These modules need to be built-in, meaning the checkbox should contain *, not M.

Processor type and features->Linux guest support->Xen guest support

Device Drivers —> Block devices —> Xen virtual block device support
Device Drivers —> Block devices —> Xen block-device backend driver

Device Drivers —> Xen driver support: It is recommended to select all options below.

Network drivers:

Device Drivers —> Network device support —> Xen network device frontend driver
Device Drivers —> Network device support —> Xen backend network device

After completion, start compiling. Here we use vzImage, so the compiled core is compressed.

[root@iZ28yx1yevuZ ~]#make -j 16 bzImage

(This process will be very long. To prevent terminal disconnection from ruining previous efforts, it is recommended to execute operations under screen. My test server has 16 cores, so I specified 16 jobs here to accelerate compilation.)

You can see that all 16 cores are fully utilized

After completion, compile and install the modules sequentially:

[root@iZ28yx1yevuZ ~]#make -j16 modules
[root@iZ28yx1yevuZ ~]#make -j16 modules_install
[root@iZ28yx1yevuZ ~]#make -j16 install

After completion, check the grub file. There are currently three boot entries:

root@iZ28yx1yevuZ ~]#cat /etc/grub2.cfg |egrep ^menuentry

Check the current default boot entry, which is the 3.10.0 kernel:

root@iZ28yx1yevuZ linux-4.1.6]# grub2-editenv list
saved_entry=CentOS Linux (3.10.0-123.9.3.el7.x86_64) 7 (Core)

Change the default boot kernel to our newly installed version 4.1.6:

[root@iZ28yx1yevuZ linux-4.1.6]# grub2-set-default "CentOS Linux (4.1.6) 7 (Core)"

The default boot entry is now the latest kernel. Restart to test:

root@iZ28yx1yevuZ linux-4.1.6]# grub2-editenv list
saved_entry=CentOS Linux (4.1.6) 7 (Core)
[root@iZ28yx1yevuZ linux-4.1.6]# reboot

The default selection is now the 4.1.6 kernel:

After normal startup, test again. The kernel is now the latest version.