Difference between revisions of "Building the Linux Kernel"
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# EMAC Software Development Kit [[ Installing_EMAC_OE_4.0_SDK | OE 4 ]] or [[Installing_EMAC_OE_5.0_SDK | OE 5 ]] | # EMAC Software Development Kit [[ Installing_EMAC_OE_4.0_SDK | OE 4 ]] or [[Installing_EMAC_OE_5.0_SDK | OE 5 ]] | ||
| − | # Linux kernel source for target hardware (provided via EMAC public [http://git.emacinc.com/ GIT server] ) | + | # Linux kernel source for target hardware (provided via EMAC public [http://git.emacinc.com/Linux-Kernel GIT server] ) |
# [ftp://ftp.emacinc.com/EMAC_Linux/SDK/kernel-build-cross.tar.gz Kernel build script] | # [ftp://ftp.emacinc.com/EMAC_Linux/SDK/kernel-build-cross.tar.gz Kernel build script] | ||
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==Configuring the Kernel== | ==Configuring the Kernel== | ||
| − | The first step for building the kernel is to configure it as desired. It is recommended to start with the kernel configuration file used by EMAC to build the kernel for the target device. Starting with EMAC OE 5, the kernel configuration can be | + | The first step for building the kernel is to configure it as desired. It is recommended to start with the kernel configuration file used by EMAC to build the kernel for the target device. Starting with EMAC OE 5.0, the kernel configuration can be |
obtained on a running board from /proc/config.gz. Please contact [http://www.emacinc.com/support EMAC support] | obtained on a running board from /proc/config.gz. Please contact [http://www.emacinc.com/support EMAC support] | ||
for earlier EMAC OE versions. | for earlier EMAC OE versions. | ||
| Line 29: | Line 29: | ||
1. Copy the default configuration file to the same directory as the kernel source tree and kernel-build-cross.sh and rename it defconfig. | 1. Copy the default configuration file to the same directory as the kernel source tree and kernel-build-cross.sh and rename it defconfig. | ||
| − | * The kernel-build-cross script accepts the SOURCE_TREE as the first argument and either config or build as the second argument. Optionally, a third argument, BUILD_SUFFIX may be supplied as a suffix to add to the build directory. BUILD_SUFFIX is commonly used to add a | + | * The kernel-build-cross script accepts the SOURCE_TREE as the first argument and either config or build as the second argument. Optionally, a third argument, BUILD_SUFFIX may be supplied as a suffix to add to the build directory. BUILD_SUFFIX is commonly used to add a tag or machine name to a build. |
| − | {{cli | username=developer | hostname=ldc |./kernel-build-cross.sh linux- | + | {{cli | username=developer | hostname=ldc |./kernel-build-cross.sh linux-emac config som9x25}} |
* The kernel menu-driven configuration utility will be displayed. Features can be selected/deselected to be built into the kernel. Some features can be built as a loadable module, denoted by < >, and not built directly into the kernel. | * The kernel menu-driven configuration utility will be displayed. Features can be selected/deselected to be built into the kernel. Some features can be built as a loadable module, denoted by < >, and not built directly into the kernel. | ||
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1. Run the kernel-build-cross script again with the build option, this time using the same build-suffix used in the configuration step. | 1. Run the kernel-build-cross script again with the build option, this time using the same build-suffix used in the configuration step. | ||
| − | {{cli | username=developer | hostname=ldc |./kernel-build-cross.sh linux- | + | {{cli | username=developer | hostname=ldc |./kernel-build-cross.sh linux-emac build som9x25}} |
* The kernel will begin compiling now. This will take several minutes to complete depending on the kernel configuration and the speed of the development machine. Only move on to the next step if the build completes with no errors. | * The kernel will begin compiling now. This will take several minutes to complete depending on the kernel configuration and the speed of the development machine. Only move on to the next step if the build completes with no errors. | ||
| − | * The new kernel image will be in the <code>build- | + | * The new kernel image will be in the <code>build-4.9.224-som9x25/Install/boot</code> directory. For the 3.10 and later device tree enabled ARM kernels, the image name will be a zImage. Also, the desired device tree blob (*.dtb) needs to be appended to the kernel. For earlier versions of the kernel, a uImage will be generated that can be loaded directly from U-Boot. X86 boards use a bzImage. |
{{clo}} | {{clo}} | ||
| − | {{clio | username=developer | hostname=ldc |cd build- | + | {{clio | username=developer | hostname=ldc |cd build-4.9.224-som9x25/Install/boot}} |
| − | {{clio | username=developer | hostname=ldc |cat zImage- | + | {{clio | username=developer | hostname=ldc |cat zImage-4.9.224 som-9x25-150es.dtb > zImage-som9x25}} |
{{clos}} | {{clos}} | ||
This is the image that will get loaded onto the board and executed by the bootloader. To load the new kernel onto the target machine, see the [[Loading Linux Kernels Onto a Board]] page. | This is the image that will get loaded onto the board and executed by the bootloader. To load the new kernel onto the target machine, see the [[Loading Linux Kernels Onto a Board]] page. | ||
| − | The build script will also create an archive of all of the modules created during the build process and place it in the <code>build- | + | The build script will also create an archive of all of the modules created during the build process and place it in the <code>build-4.9.225-som9x25/Install/</code> directory. The archive will be called <code>modules.tar.gz</code>. |
</cl> | </cl> | ||
==Loading Kernel Modules== | ==Loading Kernel Modules== | ||
| − | + | After re-compiling the kernel, it is recommended to load the corresponding kernel modules. | |
| + | |||
To reload the modules: | To reload the modules: | ||
<cl> | <cl> | ||
| − | 1. Copy the archive to the root of the filesystem of the target machine | + | 1. Make sure that the root flash is mounted read/write before copying the modules to the target. |
| + | |||
| + | * Copy the archive to the root of the filesystem of the target machine | ||
| − | {{cli | username=developer | hostname=ldc |scp build- | + | {{cli | username=developer | hostname=ldc |scp build-4.9.224-som9x25/Install/modules.tar.gz root@1IP_ADDRESS:/ }} |
* Log onto the target machine | * Log onto the target machine | ||
| Line 73: | Line 76: | ||
{{cli | username=developer | hostname=ldc |ssh root@IP_ADDRESS}} | {{cli | username=developer | hostname=ldc |ssh root@IP_ADDRESS}} | ||
| − | * Extract the kernel modules archive and force the kernel to reload the modules | + | * Extract the kernel modules archive and force the kernel to reload the modules. |
{{clo}} | {{clo}} | ||
Latest revision as of 11:32, 26 September 2020
This page covers the process of configuring and compiling the Linux kernel using the EMAC kernel build script. This process assumes that you have already acquired the following software:
- EMAC Software Development Kit OE 4 or OE 5
- Linux kernel source for target hardware (provided via EMAC public GIT server )
- Kernel build script
The example below will assume that a kernel image for the SoM-9x25 module will be created, although the instructions apply to other hardware as well assuming that the correct SDK, kernel tree, and build script is used.
Contents
Setup
The steps below assume that the kernel-build-cross.sh script is
located in the same directory as the kernel tree. Be sure to modify the environment.cfg.sh script for the correct
architecture and EMAC OE version.
Configuring the Kernel
The first step for building the kernel is to configure it as desired. It is recommended to start with the kernel configuration file used by EMAC to build the kernel for the target device. Starting with EMAC OE 5.0, the kernel configuration can be
obtained on a running board from /proc/config.gz. Please contact EMAC support
for earlier EMAC OE versions.
The following are steps to configure the kernel:
-
Copy the default configuration file to the same directory as the kernel source tree and kernel-build-cross.sh and rename it defconfig.
-
The kernel-build-cross script accepts the SOURCE_TREE as the first argument and either config or build as the second argument. Optionally, a third argument, BUILD_SUFFIX may be supplied as a suffix to add to the build directory. BUILD_SUFFIX is commonly used to add a tag or machine name to a build.
developer@ldc:~#./kernel-build-cross.sh linux-emac config som9x25 -
The kernel menu-driven configuration utility will be displayed. Features can be selected/deselected to be built into the kernel. Some features can be built as a loadable module, denoted by < >, and not built directly into the kernel.
WARNING! Disabling or modularizing some kernel features may prevent the kernel from starting correctly or at all.
Use the space bar to select an option or the 'm' key to configure the selected option as a module. Select
Exitto close the kernel configuration menu and save the configuration to the newly created build directory. When the same build-suffix is used for subsequent builds, this configuration will be used.
Building the Kernel
-
Run the kernel-build-cross script again with the build option, this time using the same build-suffix used in the configuration step.
developer@ldc:~#./kernel-build-cross.sh linux-emac build som9x25 -
The kernel will begin compiling now. This will take several minutes to complete depending on the kernel configuration and the speed of the development machine. Only move on to the next step if the build completes with no errors.
-
The new kernel image will be in the
build-4.9.224-som9x25/Install/bootdirectory. For the 3.10 and later device tree enabled ARM kernels, the image name will be a zImage. Also, the desired device tree blob (*.dtb) needs to be appended to the kernel. For earlier versions of the kernel, a uImage will be generated that can be loaded directly from U-Boot. X86 boards use a bzImage.developer@ldc:~#cd build-4.9.224-som9x25/Install/bootdeveloper@ldc:~#cat zImage-4.9.224 som-9x25-150es.dtb > zImage-som9x25This is the image that will get loaded onto the board and executed by the bootloader. To load the new kernel onto the target machine, see the Loading Linux Kernels Onto a Board page.
The build script will also create an archive of all of the modules created during the build process and place it in the
build-4.9.225-som9x25/Install/directory. The archive will be calledmodules.tar.gz.
Loading Kernel Modules
After re-compiling the kernel, it is recommended to load the corresponding kernel modules.
To reload the modules:
-
Make sure that the root flash is mounted read/write before copying the modules to the target.
-
Copy the archive to the root of the filesystem of the target machine
developer@ldc:~#scp build-4.9.224-som9x25/Install/modules.tar.gz root@1IP_ADDRESS:/ -
Log onto the target machine
developer@ldc:~#ssh root@IP_ADDRESS -
Extract the kernel modules archive and force the kernel to reload the modules.
root@som9x25:~#cd /root@som9x25:~#tar xzvf modules.tar.gzroot@som9x25:~#depmod -aroot@som9x25:~#reboot
