Difference between revisions of "CM-T3730: Linux: Kernel"

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== Overview ==
 
== Overview ==
−
Linux kernel for CM-T3730 modules provides support for on-board peripherals and abstracts the functionality provided by the hardware. Current support coverage is specified at [http://www.compulab.co.il/t3730/html/t3730-os-support.htm O/S support coverage map] page. CompuLab provides ready-to-run binary kernel images, and source code of the modifications and additions made to the Linux kernel to work properly with CM-T3730 modules.
+
Linux kernel for CM-T3730 modules provides support for on-board peripherals and abstracts the functionality provided by the hardware.
 +
Current support coverage is specified at [http://compulab.co.il/products/availability-of-os-and-drivers-for-cm-t3730-sbc-t3730/ O/S support coverage map] page.
 +
CompuLab provides ready-to-run binary kernel images, and source code of the modifications and additions made to the Linux kernel to work properly with CM-T3730 modules.
 
Most of the CM-T3730 functionality is merged into the mainline kernel starting from 3.1 release.
 
Most of the CM-T3730 functionality is merged into the mainline kernel starting from 3.1 release.
  
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The default kernel command line defines primary console, default display settings, root device and root filesystem type.<br>
 
The default kernel command line defines primary console, default display settings, root device and root filesystem type.<br>
 
Setting U-Boot {{parameter|bootargs}} environment variable overrides default kernel command line and can be used to set desired kernel parameters.
 
Setting U-Boot {{parameter|bootargs}} environment variable overrides default kernel command line and can be used to set desired kernel parameters.
 +
 +
{{Note|If the MMC/SD Card is used as your root filesystem device, Linux kernel command line must have the following parameter appended: {{parameter|mmc_core.removable&#61;0}} }}
  
 
== Building kernel for CM-T3730 ==
 
== Building kernel for CM-T3730 ==
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There are several options for cross-compilation toolchain setup. You can either compile your cross-compiler or use an already built cross-compiler. The cross-compiler should support the ARM embedded-application binary interface ("[http://en.wikipedia.org/wiki/Application_binary_interface#EABI EABI]")
 
There are several options for cross-compilation toolchain setup. You can either compile your cross-compiler or use an already built cross-compiler. The cross-compiler should support the ARM embedded-application binary interface ("[http://en.wikipedia.org/wiki/Application_binary_interface#EABI EABI]")
 
* Pre-built toolchain (recommended):
 
* Pre-built toolchain (recommended):
−
** [http://www.codesourcery.com/sgpp/lite/arm/portal/release1294 CodeSourcery]
+
** [http://www.mentor.com/embedded-software/sourcery-tools/sourcery-codebench/editions/lite-edition/ Sourcery CodeBench Lite]
 
* Tools for creating cross-compilers:
 
* Tools for creating cross-compilers:
 
** [http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool Crosstool-ng]: Builds a cross-compiler from source. Non-distribution specific.
 
** [http://ymorin.is-a-geek.org/dokuwiki/projects/crosstool Crosstool-ng]: Builds a cross-compiler from source. Non-distribution specific.
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=== Getting kernel sources ===
 
=== Getting kernel sources ===
−
There are two ways to get Linux kernel sources that can be used as a baseline for CM-T3730 kernel. You can create a copy of linux-omap git tree or download a snapshot and extract it. We assume that you have created {{filename|/home/development/cm-t3730/kernel}} directory for CM-T3730 kernel development.
+
There are two ways to get Linux kernel sources that can be used as a baseline for CM-T3730 kernel. You can create a copy of linux-stable git tree or download a snapshot and extract it. We assume that you have created {{filename|/home/development/cm-t3730/kernel}} directory for CM-T3730 kernel development.
 
==== Snapshot download ====
 
==== Snapshot download ====
−
* Download [http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=snapshot;h=02f8c6aee8df3cdc935e9bdd4f2d020306035dbe;sf=tgz v3.0] snapshot with your web browser. Note, that tools like {{cmd|wget}} and {{cmd|curl}} will not work here.
+
* Download [http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=snapshot;h=091ce3d38e5e57cf7dd44d66335725910e928f59;sf=tgz v3.0.32] snapshot with your web browser. Note, that tools like {{cmd|wget}} and {{cmd|curl}} will not work here.
−
* Extract the downloaded archive {{filename|linux-02f8c6a.tar.gz}}
+
* Extract the downloaded archive {{filename|linux-stable-091ce3d.tar.gz}}
 
<pre>
 
<pre>
 
cd /home/development/cm-t3730/kernel
 
cd /home/development/cm-t3730/kernel
−
tar xzvf /path/to/downloaded/linux-02f8c6a.tar.gz
+
tar xzvf /path/to/downloaded/linux-stable-091ce3d.tar.gz
−
mv linux-02f8c6a linux-cm-t3730
+
mv linux-stable-091ce3d linux-cm-t3730
 
</pre>
 
</pre>
 
: This will create {{filename|/home/development/cm-t3730/kernel/linux-cm-t3730}} directory containing linux kernel tree.
 
: This will create {{filename|/home/development/cm-t3730/kernel/linux-cm-t3730}} directory containing linux kernel tree.
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<pre>
 
<pre>
 
cd /home/development/cm-t3730/kernel/linux-cm-t3730
 
cd /home/development/cm-t3730/kernel/linux-cm-t3730
−
patch -p1 < /path/to/t3730-linux/kernel/linux-3.0-cm-t3730-1.patch
+
patch -p1 < /path/to/t3730-linux/kernel/linux-3.0.32-cm-t3730-2.patch
−
</pre>
 
−
* Copy the CM-T3730 kernel configuration file
 
−
<pre>
 
−
cd /home/development/cm-t3730/kernel/linux-cm-t3730
 
−
cp /path/to/t3730-linux/kernel/linux-3.0-cm-t3730-1.defconfig arch/arm/configs/cm_t3730_defconfig
 
 
</pre>
 
</pre>
  
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<pre>
 
<pre>
 
cd /home/development/cm-t3730/kernel
 
cd /home/development/cm-t3730/kernel
−
git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux-cm-t3730
+
git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-cm-t3730
 
</pre>
 
</pre>
−
* Create a branch for CM-T3730 development. The CM-T3730 patches are generated vs. v3.0 tag (02f8c6aee8df3cdc935e9bdd4f2d020306035dbe commit) in the linux tree. It is recommended to use exactly the same baseline to avoid merge conflicts.
+
* Create a branch for CM-T3730 development. The CM-T3730 patches are generated vs. v3.0.32 tag (091ce3d38e5e57cf7dd44d66335725910e928f59 commit) in the linux tree. It is recommended to use exactly the same baseline to avoid merge conflicts.
 
<pre>
 
<pre>
−
git checkout -b cm-t3730-dev v3.0
+
git checkout -b cm-t3730-dev v3.0.32
 
</pre>
 
</pre>
 
* Apply the CM-T3730 patch
 
* Apply the CM-T3730 patch
 
<pre>
 
<pre>
 
cd /home/development/cm-t3730/kernel/linux-cm-t3730
 
cd /home/development/cm-t3730/kernel/linux-cm-t3730
−
git apply /path/to/t3730-linux/kernel/linux-3.0-cm-t3730-1.patch
+
git apply /path/to/t3730-linux/kernel/linux-3.0.32-cm-t3730-2.patch
−
</pre>
 
−
* Copy the CM-T3730 kernel configuration file
 
−
<pre>
 
−
cd /home/development/cm-t3730/kernel/linux-cm-t3730
 
−
cp /path/to/t3730-linux/kernel/linux-3.0-cm-t3730-1.defconfig arch/arm/configs/cm_t3730_defconfig
 
 
</pre>
 
</pre>
 +
 +
{{Note|Future stable kernel versions of 3.0 can also be used by checking out any later tag of v3.0.y stable kernel tree.}}
  
 
=== Building the kernel ===
 
=== Building the kernel ===

Revision as of 06:08, 5 June 2012

Overview

Linux kernel for CM-T3730 modules provides support for on-board peripherals and abstracts the functionality provided by the hardware. Current support coverage is specified at O/S support coverage map page. CompuLab provides ready-to-run binary kernel images, and source code of the modifications and additions made to the Linux kernel to work properly with CM-T3730 modules. Most of the CM-T3730 functionality is merged into the mainline kernel starting from 3.1 release.

Kernel command line

The Linux kernel for CM-T3730 is shipped with built-in command line parameters: 

root=/dev/mmcblk0p3 rootwait console=ttyO2,115200 omapfb.mode=dvi:1024x768-24@60 omapfb.vram=1:4M vram=8M

The default kernel command line defines primary console, default display settings, root device and root filesystem type.
Setting U-Boot bootargs environment variable overrides default kernel command line and can be used to set desired kernel parameters.


Admolition note.png If the MMC/SD Card is used as your root filesystem device, Linux kernel command line must have the following parameter appended: mmc_core.removable=0

Building kernel for CM-T3730

Cross-Compiler

There are several options for cross-compilation toolchain setup. You can either compile your cross-compiler or use an already built cross-compiler. The cross-compiler should support the ARM embedded-application binary interface ("EABI")

  • Pre-built toolchain (recommended):
  • Tools for creating cross-compilers:
    • Crosstool-ng: Builds a cross-compiler from source. Non-distribution specific.
    • Crossdev: Gentoo's cross-compiler builder. Needs Gentoo.

U-Boot mkimage tool

U-Boot mkimage utility is required in order to create kernel images that can be loaded by the CM-T3730 bootloader. You can download prebuilt mkimage binary or build it yourself: 

mkdir ~/tmp
cd tmp
wget ftp://ftp.denx.de/pub/u-boot/u-boot-latest.tar.bz2
tar -xjvf u-boot-latest.tar.bz2
cd u-boot-<version>
touch include/config.{h,mk}
make tools
sudo install tools/mkimage /usr/local/bin

Getting kernel sources

There are two ways to get Linux kernel sources that can be used as a baseline for CM-T3730 kernel. You can create a copy of linux-stable git tree or download a snapshot and extract it. We assume that you have created /home/development/cm-t3730/kernel directory for CM-T3730 kernel development.

Snapshot download

  • Download v3.0.32 snapshot with your web browser. Note, that tools like wget and curl will not work here.
  • Extract the downloaded archive linux-stable-091ce3d.tar.gz
cd /home/development/cm-t3730/kernel
tar xzvf /path/to/downloaded/linux-stable-091ce3d.tar.gz
mv linux-stable-091ce3d linux-cm-t3730
This will create /home/development/cm-t3730/kernel/linux-cm-t3730 directory containing linux kernel tree.
  • Apply the CM-T3730 patch
cd /home/development/cm-t3730/kernel/linux-cm-t3730
patch -p1 < /path/to/t3730-linux/kernel/linux-3.0.32-cm-t3730-2.patch

Git clone

  • Install git version control system.
  • Create a clone of linux kernel tree
cd /home/development/cm-t3730/kernel
git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-cm-t3730
  • Create a branch for CM-T3730 development. The CM-T3730 patches are generated vs. v3.0.32 tag (091ce3d38e5e57cf7dd44d66335725910e928f59 commit) in the linux tree. It is recommended to use exactly the same baseline to avoid merge conflicts.
git checkout -b cm-t3730-dev v3.0.32
  • Apply the CM-T3730 patch
cd /home/development/cm-t3730/kernel/linux-cm-t3730
git apply /path/to/t3730-linux/kernel/linux-3.0.32-cm-t3730-2.patch


Admolition note.png Future stable kernel versions of 3.0 can also be used by checking out any later tag of v3.0.y stable kernel tree.

Building the kernel

export ARCH=arm
export CROSS_COMPILE=arm-none-linux-eabi-
make cm_t3730_defconfig
make menuconfig
make && make uImage && \
     INSTALL_MOD_PATH=/home/development/cm-t3730/rootfs make modules_install

In the example above, the Linux kernel image (uImage) will be created in /home/development/cm-t3730/kernel/linux-cm-t3730/arch/arm/boot, and the loadable kernel modules will be installed into the /home/development/cm-t3730/rootfs/lib/modules directory.
When the CM-T3730 is booted with the kernel image created as described above and with networked root filesystem at /home/development/cm-t3730/rootfs/, the system will be able to load the kernel modules properly, thus avoiding module version problems.

See also

Retrieved from "https://mediawiki.compulab.com/w/index.php?title=CM-T3730:_Linux:_Kernel&oldid=1289"