Build Linux Kernel from Source Code
Use version 9.2 of the Arm releases binary toolchains to cross-compile software for Toradex modules:
- For 32 bit Arm: gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz
- For 64 bit Arm: gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz
You have to choose to download either the 32 bit or 64 bit Arm cross-toolchain, according to the architecture of your Computer on Module SoC. Select the correct one from the tabs below:
To install the toolchain on your host machine, download and unpack the tar.xz file. From the command-line:
$ cd ~ $ wget -O gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz "https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz?revision=fed31ee5-2ed7-40c8-9e0e-474299a3c4ac&la=en&hash=76DAF56606E7CB66CC5B5B33D8FB90D9F24C9D20" $ tar xvf gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz $ ln -s gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf gcc-linaro Or you can download the toolchain from Arm website.
The U-Boot and Linux makefiles use the environment variables ARCH/CROSS_COMPILE to configure and call the compiler correctly. Therefore, these environment variables must be exported in any shell instance that will run configure/compile commands to build U-Boot or Linux for the target module.
$ export ARCH=arm $ export DTC_FLAGS="-@" $ export PATH=~/gcc-linaro/bin/:$PATH $ export CROSS_COMPILE=arm-none-linux-gnueabihf- You can put those commands into a file and source that file to export it more easily, e.g.:
$ echo "export ARCH=arm" >> ~/export_compiler $ echo "export DTC_FLAGS='-@'" >> ~/export_compiler $ echo "export PATH=~/gcc-linaro/bin/:$PATH" >> ~/export_compiler $ echo "export CROSS_COMPILE=arm-none-linux-gnueabihf-" >> ~/export_compiler $ source ~/export_compiler To install the toolchain on your host machine, download and unpack the tar.xz file. From the command-line:
$ cd ~ $ wget -O gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz "https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz?revision=61c3be5d-5175-4db6-9030-b565aae9f766&la=en&hash=0A37024B42028A9616F56A51C2D20755C5EBBCD7" $ tar xvf gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz $ ln -s gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu gcc-linaro Or you can download the toolchain from Arm website.
The U-Boot and Linux makefiles use the environment variables ARCH/CROSS_COMPILE to configure and call the compiler correctly. Therefore, these environment variables must be exported in any shell instance that will run configure/compile commands to build U-Boot or Linux for the target module.
$ export ARCH=arm64 $ export DTC_FLAGS="-@" $ export PATH=~/gcc-linaro/bin/:$PATH $ export CROSS_COMPILE=aarch64-none-linux-gnu- You can put those commands into a file and source that file to export it more easily, E.g.:
$ echo "export ARCH=arm64" >> ~/export_compiler $ echo "export DTC_FLAGS='-@'" >> ~/export_compiler $ echo "export PATH=~/gcc-linaro/bin/:$PATH" >> ~/export_compiler $ echo "export CROSS_COMPILE=aarch64-none-linux-gnu-" >> ~/export_compiler $ source ~/export_compiler Install Tools and Dependencies
Build Host
You need some essential build tools to compile the Kernel or DTC. Most are likely part of your distro’s standard install.
$ sudo dnf install bc gcc git ncurses-devel lzop make perl openssl-devel bison flex diffutils $ sudo apt-get install bc build-essential git libncurses5-dev lzop perl libssl-dev bison flex U-Boot Tools
The uImage target of the Linux kernel compilation needs a recent mkimage tool.
One can install the Fedora package uboot-tools :
$ sudo dnf install uboot-tools Or with the corresponding Debian/Ubuntu package u-boot-tools :
$ sudo apt-get install u-boot-tools Alternatively, mkimage tool is also built during the U-Boot compilation. You can follow the U-Boot building instructions as explained further in this article, and after that, include it in PATH.
Kernel Version Information
The required git branch and Linux binaries to be used depend on module type and BSP version, as we will explain in this article.
For a high-level overview of the BSP Versions, check out our Embedded Linux Release Matrix. There you will find the version information of the Linux kernel, U-Boot, Yocto/OpenEmbedded, the Toradex BSP, and Linux images, along with release dates.
Upstream-based Kernel
| SoC | Kernel Git Branch | Kernel Configuration | Kernel Binary |
|---|---|---|---|
| i.MX 8MM/8MP | v6.1 | defconfig | arch/arm64/boot/Image.gz |
| i.MX 7 | v6.1 | imx_v6_v7_defconfig | arch/arm/boot/zImage |
| i.MX 6 | v6.1 | imx_v6_v7_defconfig | arch/arm/boot/zImage |
| i.MX 6ULL | v6.1 | imx_v6_v7_defconfig | arch/arm/boot/zImage |
Downstream-based Kernel
| SoC | Kernel Git Branch | Kernel Configuration | Kernel Binary |
|---|---|---|---|
| i.MX 8MM/8MP | toradex_5.15-2.0.x-imx | toradex_defconfig | arch/arm64/boot/Image.gz |
| SoC | Kernel Git Branch | Kernel Configuration | Kernel Binary |
|---|---|---|---|
| i.MX 8/8MM/8MP | toradex_5.15-2.1.x-imx | toradex_defconfig | arch/arm64/boot/Image.gz |
Device Tree Binaries Information
| SoC | Device Tree |
|---|---|
| i.MX 8/8MM/8MP | imx8qm-apalis-eval.dtb imx8qm-apalis-ixora-v1.1.dtb imx8qm-apalis-v1.1-eval.dtb imx8qm-apalis-v1.1-ixora-v1.1.dtb imx8qm-apalis-v1.1-ixora-v1.2.dtb imx8qp-apalis-v1.1-eval.dtb imx8qp-apalis-v1.1-ixora-v1.1.dtb imx8qp-apalis-v1.1-ixora-v1.2.dtb imx8mm-verdin-nonwifi-dahlia.dtb imx8mm-verdin-nonwifi-dev.dtb imx8mm-verdin-wifi-dahlia.dtb imx8mm-verdin-wifi-dev.dtb imx8mp-verdin-nonwifi-dahlia.dtb imx8mp-verdin-nonwifi-dev.dtb imx8mp-verdin-wifi-dahlia.dtb imx8mp-verdin-wifi-dev.dtb |
| i.MX 7 | imx7d-colibri-aster.dtb imx7d-colibri-emmc-aster.dtb imx7d-colibri-emmc-eval-v3.dtb imx7d-colibri-eval-v3.dtb imx7s-colibri-aster.dtb imx7s-colibri-eval-v3.dtb |
| i.MX 6 | imx6q-apalis-eval.dtb imx6q-apalis-ixora.dtb imx6q-apalis-ixora-v1.1.dtb imx6q-apalis-ixora-v1.2.dtb imx6dl-colibri-eval-v3.dtb |
| i.MX 6ULL | imx6ull-colibri-emmc-eval-v3.dtb imx6ull-colibri-eval-v3.dtb imx6ull-colibri-wifi-eval-v3.dtb |
Building Linux Kernel
Download the Linux Kernel Source
Obtain the kernel source code using Git:
$ mkdir -p ~/workdir $ cd ~/workdir $ git clone -b git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git $ mkdir -p ~/workdir $ cd ~/workdir $ git clone -b git://git.toradex.com/linux-toradex.git Replace by the Kernel Git Branch for your specific configuration. Click below to expand the version information. Check the section Kernel Version for this specific information.
If additional patches are provided, apply them as follows: git am .
If your company firewall/gateway inhibit the git protocol, you may use HTTP or HTTPS instead (e.g. git clone https://git.toradex.com/linux-toradex.git ).
Kernel Configuration
Our kernel tree provides default kernel configurations for our modules:
Ensure the environment is configured for cross-compilation as explained in the toolchain chapter.
Set the default configuration:
$ cd ~/workdir/linux-toradex $ make Replace by the Kernel Configuration for your specific configuration. Check the section Kernel Version for this specific information.
At this point, one may alter the kernel configuration by either editing .config directly (e.g., setting CONFIG_* to either =y or =m aka as module) or use one of the kernel configuration utilities included, e.g.:
Kernel Compilation
Depending on the module, different kernel image types are used. Furthermore, some kernels require a device tree to describe the system’s hardware (see Device Tree Customization for details).
Our kernel configurations build some drivers as kernel modules.
To assure module compatibility, the Kernel refuses to load modules with a ‘vermagic’ string that does not match its own. On top of that, the modules are stored under a directory named after the version string.
Thus one usually needs to compile and deploy the kernel modules together with the Kernel in order to use them.
To compile the Kernel & device tree:
$ make -j$(nproc) Image.gz 2>&1 | tee build.log $ make DTC_FLAGS="-@" freescale/.dtb Replace by the Device Tree for your specific configuration. Check the section Device Tree Binaries Information for this specific information.
To compile the kernel & device tree:
$ make -j$(nproc) zImage 2>&1 | tee build.log $ make DTC_FLAGS="-@" .dtb Replace by the Device Tree for your specific configuration. Check the section Device Tree Binaries Information for this specific information.
The Linux kernel for our i.MX7 based modules can show linking issues when using the gold linker:
arm-angstrom-linux-gnueabi-ld: --pic-veneer: unknown option arm-angstrom-linux-gnueabi-ld: use the --help option for usage information The recommended solution is to just revert to using the regular bfd linker as follows:
$ make -j$(nproc) zImage LD=$ld.bfd | tee build.log To compile the kernel & device tree for BSP 2.8b2 or newer:
$ make -j$(nproc) zImage LOADADDR=10008000 2>&1 | tee build.log $ make DTC_FLAGS="-@" .dtb Replace by the Device Tree for your specific configuration. Check the section Device Tree Binaries Information for this specific information.
To compile the kernel & device tree:
$ make -j$(nproc) zImage 2>&1 | tee build.log $ make DTC_FLAGS="-@" .dtb Replace by the Device Tree for your specific configuration. Check the section Device Tree Binaries Information for this specific information.
To compile the kernel & device tree for BSP 2.8 or older:
The Linux kernel for our i.MX 6ULL based modules can show linking issues when using the gold linker:
arm-angstrom-linux-gnueabi-ld: --pic-veneer: unknown option arm-angstrom-linux-gnueabi-ld: use the --help option for usage information The recommended solution is to just revert to using the regular bfd linker as follows:
$ make -j$(nproc) zImage LD=$ld.bfd | tee build.log