View source for Building Linux kernel (BELK/BXELK)

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{{Applies To Bora}}
{{Applies To BoraX}}
{{Applies To BoraLite}}
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{{ImportantMessage|text=As the structure of the BELK/BXELK is based on several tools, it is strongly recommended the reading of [[BORA_SOM/BELK-L/General/Logical_structure_of_BELK|this document]] first.
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== History ==
{| class="wikitable" border="1"
!Version
!Date
!BELK version
!Notes
|-
|{{oldid|6392|1.0.0}}
|November 2015
|[[Bora_Embedded_Linux_Kit_(BELK)#BELK_software_components|3.0.0]]
|First release
|-
|1.1.0
|August 2018
|[[BELK/BXELK_software_components#BELK_4.0.0_.2F_BXELK_2.0.0|4.0.0]]
|Update for BELK-4.x.x
|-
|1.1.1
|January 2020
|[[BELK/BXELK_software_components#BELK_4.1.0|4.1.0]]
|Update for BELK-4.1.x
|-
|}

<section begin=BELK/>
==Building Linux kernel==
It is assumed that the development environment has been set up properly as described [[BORA_SOM/BELK-L/Development/Build_system|here]].
*start the Linux development server and login into the system
*assuming that a local repository has not been created, clone the remote Linux git repository (the “-b” option is used to automatically checkout the current branch):

<pre>
git clone git@git.dave.eu:dave/bora/linux-xlnx.git -b bora-4.x.x
</pre>

*setup the server environment (please refer to [[BORA_SOM/BELK-L/Development/Build_system#Pre-built_toolchain|this section]])
*enter the source tree directory and run the following commands:

<pre>
make bora_defconfig
make UIMAGE_LOADADDR=0x8000 uImage bora.dtb
</pre>

:The former command selects the default BORA configuration, while the latter builds the kernel binary image with the required u-boot header and the kernel device tree. Please note that the <code>mkimage</code> tool is required for building the <code>uImage</code> binary. This tool must be installed on the Linux development server (please refer to the package manager of the Linux distribution).

=== update the kernel configuration ===
Default Linux kernel configuration can be changed by using the standard <code>menuconfig</code> or <code>nconfig</code> as make ''target''. Subsequent builds just require <code>uImage</code> make target to update the binary image.

 make menuconfig

[[File:BELK-make-menuconfig.png | 800px]]

=== kernel modules ===
It is possible to build the kernel modules too, together with the kernel image:

 make UIMAGE_LOADADDR=0x8000 uImage '''modules''' bora.dtb

then, the built modules have to be prepared for being installed in the rfs:

 make INSTALL_MOD_PATH=''<directory_for_modules>'' modules_install

and properly copy them in the target root file system

=== tftpboot ===

Default linux kernel configuration can be changed by using the standard <code>menuconfig</code>, <code>xconfig</code>, or <code>gconfig</code> make target. Subsequent builds just require <code>uImage</code> make target to update the binary image. Once the build process is complete, the kernel binary image is stored into the <code>arch/arm/boot/uImage</code> file. Both this file and the kernel device tree can be copied to the tftp root directory (eg. <code>/tftpboot/bora/</code>) with the following commands:
<pre>
cp arch/arm/boot/uImage /tftpboot/bora
cp arch/arm/boot/dts/bora.dtb /tftpboot/bora
</pre>
<section end=BELK/>