Difference between revisions of "The Linux kernel"

Revision as of 11:30, 31 January 2011

How to cross compile the linux kernel

Embedded Linux is the use of a Linux operating system in embedded computer systems such as mobile phones, personal digital assistants, media players, set-top boxes, and other consumer electronics devices, networking equipment, machine control, industrial automation, navigation equipment and medical instruments.

Unlike desktop and server versions of Linux, embedded versions of Linux are designed for devices with relatively limited resources, such as cell phones and set-top boxes. Due to concerns such as cost and size, embedded devices usually have much less RAM and secondary storage than desktop computers, and are likely to use flash memory instead of a hard drive. Since embedded devices serve specific rather than general purposes, developers optimize their embedded Linux distributions to target specific hardware configurations and usage situations. These optimizations can include reducing the number of device drivers and software applications, and modifying the Linux kernel to be a real-time operating system.

Overview of How-To

This How-To is meant to be a starting point for people to learn build a kernel image for IGEP v2 devices as quickly and easily as possible.

This How-To works with the Ubuntu 8.04 IGEP v2.0 SDK Virtual Machine but most of the contents are valid also for other GNU/Linux distributions. We do not issue any guarantee that this will work on other distributions.

Requirements

• Ubuntu 8.04 IGEP v2.0 SDK Virtual Machine

IGEP platforms

• IGEP0020 is also know as IGEP v2 platform.
• IGEP0030 is also know as OMAP3 IGEP module.

Supported kernels

First of all setup the build environment sourcing this script

source /usr/local/poky/eabi-glibc/arm/environment-setup

or

source /usr/local/poky/eabi-glibc/environment-setup-arm-none-linux-gnueabi

if you have updated your SDK environment to latest version (see Ubuntu 8.04 IGEP v2.0 SDK Virtual Machine)

Linux OMAP v2.6.35 series (stable)

Latest stable kernel version is: 2.6.35.10-0 (20110117)

Supported platforms: IGEP0020 and IGEP0030 (OMAP35x/DM3730)

Download the IGEP Linux kernel sources and follow next steps:

wget http://downloads.igep.es/sources/linux-omap-2.6.35.tar.gz
tar xzf linux-omap-2.6.35.tar.gz
cd [kernel version]
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- <board-config>
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- menuconfig

where the last line is only required if you want to manualy modify the kernel options and

• <board-config> is igep0020_defconfig for IGEP v2 platform.
• <board-config> is igep0030_defconfig for OMAP3 IGEP module.

Then build the kernel with:

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage modules

The result will be an uImage file in arch/arm/boot directory. You can install the kernel modules to your target rootfs

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- modules_install INSTALL_MOD_PATH=[path to your target rootfs]

ISSUES

• Bluetooth: Broken due to an incompatibility with expansion board, to solve this apply this patch

diff --git a/arch/arm/mach-omap2/board-igep0020-22.c b/arch/arm/mach-omap2/board-igep0020-22.c
index 06f9809..1d6a4cf 100644
--- a/arch/arm/mach-omap2/board-igep0020-22.c
+++ b/arch/arm/mach-omap2/board-igep0020-22.c
@@ -301,7 +301,7 @@ void __init igep0022_init(void)
        igep0022_tsc2046_init();
 
        /* GPIO's for GE865 modem interface */
-       igep0022_modem_init();
+       /* igep0022_modem_init(); */
 
        /* CAN driver for Microchip 251x CAN Controller with SPI Interface */
        igep0022_mcp251x_init();

CHANGELOG

• 2011-01-17 Release 2.6.35.10-0
  • Rebased with longterm/linux-2.6.35.y
  • Add MADC driver
  • Add TIDSPBRIDGE driver
  • Fix MCSPI, disable channel after TX_ONLY transfer in PIO mode
• 2010-11-23 Release 2.6.35.9-0
  • Rebased with stable/2.6.35.9
  • Add IGEP0022 expansion support by default
  • Add EHCI support on OMAP3 IGEP module.
  • Fix modem GPIO for IGEP v2 expansion board
• 2010-11-05 Release 2.6.35.8-0
  • Rebased with stable/2.6.35.8
  • Fix libertas driver with SDIO IRQ
• 2010-10-28 Release 2.6.35.7-1
  • Add support for SDIO IRQ
  • Fix onenand bufferram management
  • Improve IGEP0020 expansion board support
    • Add support for 4.3 inch and 7.0 inch display panels
    • Fix CAN probe oops
• 2010-10-19 Release 2.6.35.7-0
  • First release for 2.6.35 series

Linux OMAP v2.6.33 series (stable)

Latest stable kernel version is: 2.6.33.7-0 (20100825)

Supported platforms: IGEP0020 and IGEP0030 (OMAP35x)

Download the IGEP Linux kernel sources and follow next steps:

wget http://downloads.igep.es/sources/linux-omap-2.6.33.tar.gz
tar xzf linux-omap-2.6.33.tar.gz
cd [kernel version]
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- <board-config>
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- menuconfig

where the last line is only required if you want to manualy modify the kernel options and

• <board-config> is igep0020_defconfig for IGEP v2 platform.
• <board-config> is igep0030_defconfig for OMAP3 IGEP module.

Then build the kernel with:

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage modules

The result will be an uImage file in arch/arm/boot directory. You can install the kernel modules to your target rootfs

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- modules_install INSTALL_MOD_PATH=[path to your target rootfs]

CHANGELOG

• 2010-08-25 Release 2.6.33.7-0
  • add SGX drivers pulled from TI SDK 3.01.00.06
• 2010-07-29 Release 2.6.33.6-0
  • add support auto RS485 direction control
  • fix bufferram management for OneNAND
  • usb: make disconnect and suspend interrupts work again
• 2010-06-11 Release 2.6.33.5-0
  • add support for OMAP3 IGEP module (igep0030)

Linux OMAP v2.6.28 series (stable)

Latest stable kernel version is: 2.6.28.10-3 (20100318)

Supported platforms: IGEP0020 (OMAP35x)

Download the IGEP v2 Linux kernel sources and follow next steps:

wget http://downloads.igep.es/sources/linux-omap-2.6.28.tar.gz
tar xzf linux-omap-2.6.28.tar.gz
cd [kernel version]
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- igep0020_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage modules

The result will be an uImage file in arch/arm/boot directory. You can install the kernel modules to your target rootfs

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- modules_install INSTALL_MOD_PATH=[path to your target rootfs]

Linux mainline tree (development)

Note: The 'master' branch is where the development work takes place and you should use this if you're after to work with the latest cutting edge developments. It is possible trunk can suffer temporary periods of instability while new features are developed and if this is undesirable we recommend using one of the release branches. Use ONLY for development purposes.

Additional patches can be found at http://patchwork.kernel.org/project/linux-omap/list

This Linux kernel is also considered as a downstream of tmlind's Linux kernel. The main difference between this tree and the linux-omap tree is that the igep OMAP tree has unpublished patches for IGEP v2 support.

Clone GIT repository from git.igep.es

git clone git://git.igep.es/pub/scm/linux-omap-2.6.git
cd linux-omap-2.6

and build with

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- omap2plus_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage modules

The result will be an uImage file in arch/arm/boot directory. You can install the kernel modules to your target rootfs

make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- modules_install INSTALL_MOD_PATH=[path to your target rootfs]