Run a custom kernel on Clear Linux with ease.
The motivation comes from wanting preempt-enabled kernels patched with BORE (Burst-Oriented Response Enhancer) CPU Scheduler.
The kernels are configured to run equally well on all x86-64 CPUs with minimum support of x86-64-v3. They include the v4l2-loopback patch and NTSync for fast kernel-backed Wine.
bore - Clear 6.11.y native kernel + preemption + BORE
bore-rt - Same features, plus the Linux realtime patch set
The Clear kernel config enables ZSTD module compression, since 41850. Thus, installation requires CL 41850 (or later) to continue i.e. kmod, toolchain, and zstd updates.
Install build-essential bundles or prerequisites for building the kernel.
The wget command is used to fetch the source archive from the web.
sudo swupd bundle-add \
bc bison c-basic devpkg-gmp devpkg-elfutils devpkg-openssl flex \
kernel-install linux-firmware lz4 make package-utils wget xz \
dkms hardware-uefi init-rdaheadThe power tweaks service is how Clear Linux sets reasonable power management
defaults. For additional tweaking and response time consistency, copy the
sample file to the /etc folder, or merge the entries manually. This requires
the clr-power service, enabled by default.
sudo cp share/clr-power-tweaks.conf /etc/.Set boot-timeout and system‐wide configuration to avoid clr‐boot‐manager
changing efi variables.
sudo mkdir -p "/etc/kernel"
sudo tee "/etc/kernel/timeout" >/dev/null <<'EOF'
5
EOF
sudo tee "/etc/kernel/update_efi_vars" >/dev/null <<'EOF'
false
EOFCopy the NTSync udev rule.
sudo mkdir -p /etc/udev/rules.d
sudo cp share/99-ntsync.rules /etc/udev/rules.d/.The GitHub repo provides auto completion for the bash shell.
git clone https://github.com/marioroy/clearmod
cd clearmod
mkdir -p ~/.local/share/bash-completion/completions
cp -a share/bash-completion/completions/* \
~/.local/share/bash-completion/completions/The fetch-src command (run first) fetches the source rpm and tar archive.
Running a realtime kernel using NVIDIA graphics requires 550 minimally.
./fetch-src
./xm-build bore | bore-rt
./xm-install bore | bore-rt [<rel>]
./xm-uninstall bore | bore-rt [<rel>]
./xm-uninstall all
./xm-kernels - list kernels and packages
./xm-purge - purge packagesThe following are the steps to fetch the stable sources, build, and install the kernel.
./fetch-src
./xm-build bore
./xm-install bore
syncTo quickly build a trimmed Linux kernel, LOCALMODCONFIG=1 will build only
the modules you have running. Therefore, make sure that all modules you will
ever need are loaded. Keyboard modules for the cpio package, CD-ROM/DVD and
EXFAT/NTFS3 filesystems, and NTSYNC are added in the SPEC files.
The default timer frequency is HZ_800. To override, define HZ=value to
1000, 800, 600, or 500. A lower Hz value may decrease power consumption
or fan speed revving up and down. On a machine with more than 32 CPU threads,
select 800 or 600 for smoother game play.
The RT variants include the real-time patch set, useful for projects with hard or soft deadlines.
./fetch-src
LOCALMODCONFIG=1 HZ=1000 ./xm-build bore
LOCALMODCONFIG=1 HZ=1000 ./xm-build bore-rt
./xm-install bore
./xm-install bore-rt
sync
The xm-kernels command lists xm* kernels only. An asterisk indicates
the kernel is live or running. One may not install over it or uninstall.
Boot into another kernel before removal via xm-uninstall.
./xm-kernels
XM boot-manager entries
* org.clearlinux.xmbore.6.11.11-210
org.clearlinux.xmbore-rt.6.11.11-210
XM installed packages (excluding dev,extra,license)
* linux-xmbore-6.11.11-210
linux-xmbore-rt-6.11.11-210The xm-install and xm-uninstall commands accept an optional argument to
specify the release number. By default, xm-install installs the most recent
build. Omitting the 2nd argument, xm-uninstall removes all releases.
Though, skips the running kernel.
./xm-uninstall bore-rt 210
Removing org.clearlinux.xmbore-rt.6.11.11-210The clr-boot-manager update command may remove older kernel versions.
Run the purge script, periodically, to uninstall packages for xm-kernels
no longer present in /lib/modules.
./xm-purgeThe /boot partition has limited space. So, no reason to install many kernels.
Build the one you want and enjoy the Clear kernel. If changing your mind later,
remember to manage and uninstall any unused kernels. Moreover, purge old files
found under the ./rpmbuild/RPMS/x86_64/ folder to free up storage space.
To limit the number of CPUs used by rpmbuild, override the %_smp_mflags
macro. Adjust the integer value to your liking.
echo "%_smp_mflags -j4" >> ~/.rpmmacrosYou may add a build script at the top level, ignored by git.
Set execute bits chmod +x build and run ./build.
#!/bin/bash
time LOCALMODCONFIG=1 HZ=1000 ./xm-build boreConfiguring PAM or security limits, allowing users to run commands with
real-time capabilities, does not work on Clear Linux. A workaround is making
a copy of chrt and giving it cap_sys_nice+ep capabilities. The +ep
indicate the capability sets effective and permitted.
chrt -f 1 echo "Aloha!"
chrt: failed to set pid 0's policy: Operation not permitted
sudo mkdir -p /usr/local/bin
sudo cp -a /usr/bin/chrt /usr/local/bin/.
sudo setcap cap_sys_nice+ep /usr/local/bin/chrt
# The path /usr/local/bin is searched before /usr/bin in $PATH env.
chrt -f 1 echo "Aloha!"
Aloha!