Compiling and Installing the Kernel

Obtaining the Kernel Source Code

Create a directory and go to the directory.

        
             mkdir -p /home/kernel-bcache
cd /home/kernel-bcache

Download the kernel source package to the /home/kernel-bcache directory.
Download address: https://repo.openeuler.org/openEuler-20.03-LTS-SP1/source/Packages/

Decompress the source package.

        
             rpm2cpio kernel-4.19.90-2012.4.0.0053.oe1.src.rpm | cpio -divm
tar -zxvf kernel.tar.gz

Configure the image source.

Use the SFTP tool to upload openEuler-***-everything-aarch64-dvd.iso to the /root directory on the server.
Create a local folder to mount the image.
1

mkdir -p /iso

Mount the ISO file to the local directory.

          
               mount /root/openEuler-***-everything-aarch64-dvd.iso /iso

Create a Yum source for the image.

          
               vi /etc/yum.repos.d/openEuler.repo

Add the following information to the file:

           
            
              
              
                [Base]
name=Base
baseurl=file:///iso
enabled=1
gpgcheck=0
priority=1

[openEuler-source]
name=openEuler-source
baseurl=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/source/
enabled=1
gpgcheck=1
gpgkey=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/source/RPM-GPG-KEY-openEuler

[openEuler-os]
name=openEuler-os
baseurl=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/OS/aarch64/
enabled=0
gpgcheck=1
gpgkey=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/OS/aarch64/RPM-GPG-KEY-openEuler

[openEuler-everything]
name=openEuler-everything
baseurl=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/everything/aarch64/
enabled=0
gpgcheck=1
gpgkey=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/everything/aarch64/RPM-GPG-KEY-openEuler

[openEuler-EPOL]
name=openEuler-epol
baseurl=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/EPOL/aarch64/
enabled=1
gpgcheck=0

[openEuler-update]
name=openEuler-update
baseurl=http://repo.openeuler.org/openEuler-20.03-LTS-SP1/update/aarch64/
enabled=1
gpgcheck=0

               

             

           
          

Install the dependency.

        
             dnf -y install ncurses-devel bison m4 flex rpm-build rpmdevtools asciidoc audit-libs-devel binutils-devel elfutils-devel elfutils-libelf-devel gtk2-devel java-1.8.0-openjdk-devel xz-devel libbabeltrace-devel libunwind-devel newt-devel numactl-devel openssl-devel pciutils-devel perl-generators python3-devel python3-docutils xmlto zlib-devel mkeuleros createrepo genisoimage

Replacing the Bcache Module

Obtain the bcache source code and save it to /home.
Download address: https://gitee.com/openeuler/kernel/tree/openEuler-1.0-LTS/kernel

Decompress the source code.

unzip openeuler-kernel-openEuler-1.0-LTS.zip

Replace the bcache.

        
             cp -rf /home/kernel/drivers/md/bcache /home/kernel-bcache/kernel/drivers/md/

Modifying the Kernel Configuration

Obtain the kernel configuration file.

        
             cd /home/kernel-bcache/kernel
cp arch/arm64/configs/openeuler_defconfig .config

Configure the bcache module.
1

make menuconfig
1. Choose Device Drivers.
2. Press Enter to access the next-level menu, and then choose Multiple device driver support (RAID and LVM).
3. Press Enter to access the next-level menu, choose Block device as cache, and press M to select the configuration.
4. Click Exit twice to return to the first-level menu.
Change the kernel page size to 4 KB.
1. Choose Kernel Features.
2. Press Enter to access the next-level menu, and choose Page size (64 KB).
3. Press Enter to access the next-level menu, and press Space to choose 4 KB.
4. Click Exit twice to save the setting and exit.
Verify the configuration file.
1. Ensure that the bcache module is enabled.
2. Ensure that the value of page size is 4 KB.

Overwrite the default configuration file.

        
             cp .config arch/arm64/configs/openeuler_defconfig

Type Y.

Creating a Kernel RPM Package

Repack the kernel source code.

        
             cd /home/kernel-bcache
tar -zcvf kernel.tar.gz kernel

Create an rpmbuild directory.

        
             mkdir -p /home/rpmbuild
cd /home/rpmbuild
mkdir -p BUILD  RPMS  SOURCES  SPECS  SRPMS

Change the default rpmbuild path.
1

vi /root/.rpmmacros
Add the following information:
1

%_topdir /home/rpmbuild

Copy the files to the rpmbuild directory.

        
             cp -r /home/kernel-bcache/* SOURCES/
cp /home/kernel-bcache/kernel.spec SPECS/
rm -rf SOURCES/kernel

Compile and create a kernel RPM package.

        
             vi /usr/lib/rpm/macros

Change %_unpackaged_files_terminate_build 1 to %_unpackaged_files_terminate_build 0.

        
             rpmbuild -bb /home/rpmbuild/SPECS/kernel.spec --with baseonly --without debug --without debuginfo

View the generated kernel RPM package.
```
ls /home/rpmbuild/RPMS/aarch64/
```

Installing the Kernel

Upload the kernel RPM package generated in Creating a Kernel RPM Package to the /home/kernel-rpm directory.
1

mkdir -p /home/kernel-rpm

Install the kernel RPM package.

        
             cd /home/kernel-rpm
dnf -y install kernel-4.19.90-2012.4.0.0053.aarch64.rpm kernel-devel-4.19.90-2012.4.0.0053.aarch64.rpm

Check the default kernel startup items.
1

grub2-editenv list
Check the default kernel version number.
- If the default version is the newly installed kernel version, skip step 4.
- Otherwise, go to step 4.
Modify the default kernel startup items.
1

cat /etc/grub2-efi.cfg | grep openEuler
In the preceding information, openEuler (4.19.90-2012.4.0.0053.aarch64) 20.03 (LTS-SP1) indicates the newly installed kernel.
```
grub2-set-default "openEuler (4.19.90-2012.4.0.0053.aarch64) 20.03 (LTS-SP1)"
```
Restart the system.
1

reboot

Parent topic: Installing the Bcache