kw-build - Build kernel#


kw (b | build) [(-i | --info)] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-n | --menu)] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-d | --doc)] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [--ccache] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-S | --cpu-scaling)] <percentage> [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-w | --warnings)] [warning-levels] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-s | --save-log-to)] <path> [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [--llvm] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-c | --clean)] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [(-f | --full-cleanup)] [--alert=(s | v | (sv | vs) | n)]
kw (b | build) [--cflags]
kw (b | build) [--from-sha <SHA>]
kw (b | build) [--verbose]


If users invoke this option without parameters, kw will look at the local Makefile and, based on that, start to build the project. This option tries to take advantage of your hardware by using the -j option with the appropriate parameter.

This command can be used in conjunction with deploy by invoking kw bd.


This command must be run inside of a kernel tree.


-i, --info:

The info option, makes so the build information such as the kernel release name and the total number of modules compiled will be displayed.

-n, --menu:

The menu option invokes the kernel menuconfig. Notice that the default menu config can be changed in the build.config file by setting a different option in menu_config. If the user is working in a cross-compile environment, it is recommended to use this option to avoid messing with the config file manually.

-d, --doc:

The doc option provides a mechanism for building the kernel-doc; by default, it will build htmldocs. Users can change the default documentation output by changing the parameter doc_type in the build.config file.

-S, --cpu-scaling:

The cpu-scaling option lets the user set whichever CPU usage they want from their CPU, basically setting the -j flag accordingly.


This option allows the user to enable ccache usage during compilation tasks, which should improve compile times in subsequent compilations. If you want, you can set this option in the build.config file.

-w, --warnings (1 | 2 | 3 | 12 | 13 | 23 | 123):

This can be used to enable compilation warnings accordingly. You can set the default log level via build.config file under the option warning_level. Please check the kernel’s make help for more info.

-s, --save-log-to path:

This option will save the full compilation log with the enabled warnings to the specified path. You can set the default log path in the build.config file via log_path option.


This option can be set to enable the usage of the LLVM toolchain during compilation/linking tasks. You can enable it by default via use_llvm option in the build.config file.

-c, --clean:

The clean option removes files generated by the kernel build system but keeps the kernel configuration. This option considers whether the user is using or not kw env.

-f, --full-cleanup:

Under the hood, this command runs make distclean, resetting the built environment to its initial/default state. In other words, it will remove files generated by the build process, including configuration files and script output. This option also considers whether or not the user is using kw env.


Verbose mode is an option that causes the kw program to display debug messages to track its progress. This functionality is very useful during the debugging process, allowing you to identify possible errors more easily.


This function provides a flexible way to pass CFLAGS when compiling a custom kernel, allowing you to customize and tune the build process to your specific needs. This is especially useful for optimizing performance and controlling generated kernel behavior.

--alert=(s | v | (sv | vs) | n):
Defines the alert behaviour upon the command completion.
s enables sound notification.
v enables visual notification.
sv or vs enables both.
n (or any other option) disables notifications (this is the default).

Build every commit after <SHA> to branch head. Useful for testing if all patches in patchset compile.


For these examples, we assume that the relevant fields in your configuration files (located by default in .kw/) have already been setup. We recommend the use of kw config for managing your local and global configurations.

For building and installing a new module version based on the current kernel version, you can use:

cd <kernel-path>
kw bd

If you want that kw become more verbose about the compilation warning, you can use:

kw build --warnings=1

Let’s say that you are doing something else and don’t want that your CPU cores to be super busy during the compilation; you can tell kw how much of the CPU utilization you are willing to give for the kernel compilation:

kw b --cpu-scaling=50

If you like to use ccache to build your kernel, you can use:

kw b --ccache

If you want to ensure that your change does not add any relevant warning, you can use:

kw b --warnings

If you want to see other warning levels, you can change the log level by using:

kw b --warnings 2

Sometimes we have a lot of error message that does not fit in the terminal buffer; in these cases it is helpful to save all logs in a file:

kw b --warnings 123 --save-log-to ALL_WARNINGS.log

If you want to use llvm:

kw b --llvm

If you want to clean your kernel:

kw b --clean

If you want to reset the kernel tree to its default, all config and script output will be removed:

kw b --full-cleanup

If you want to use cflags:

kw b --cflags "-O3 -pipe -march=native"

If you want to build every commit after HEAD~2 to HEAD:

kw b --from-sha HEAD~2

If you want to build every commit after ee3b5 to HEAD:

kw b --from-sha ee3b5