kernel development using Eclipse (OMAP4 pandaboard + 2.6.35 + Android)

Working with kernel sources

Just found out that guys in my team are using all different editors for kernel code debugging - and all not very effective enough... Of course the best solution IMHO is till gvim + ctags, but if you wish something more fancy :) you can go with Eclipse - so I've tried to set it up on my fresh Ubuntu 11.04 x64

1. Download and install toolchain
For the reasons unknown I have decided to use Linaro toolchain for my games. According to Linaro HOWTO this is as simple as entering one command for natty:
  sudo apt-get install gcc-arm-linux-gnueabi
of course, I have all my Ubuntu build tools preinstalled.


2. Download the kernel sources
Since I am going to use OMAP4 pandaboard with 2.6.35 kernel on Android - I am following instructions on OMAPpedia wiki to pull the kernel:

  git clone git://git.omapzoom.org/kernel/omap.git kernel
  git checkout -b p-android-omap-2.6.35_local remotes/origin/p-android-omap-2.6.35

Before building the kernel with latest Linaro toolchain I need to apply a patch that resolves binutils architecture issues with 2.6.35 kernel.


diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
index 884eb1f..6854066 100644
--- a/arch/arm/mach-omap2/Makefile
+++ b/arch/arm/mach-omap2/Makefile
@@ -30,8 +30,10 @@ obj-$(CONFIG_HOTPLUG_CPU) += omap-hotplug.o
  obj-$(CONFIG_ARCH_OMAP4) += omap44xx-smc.o omap4-common.o \
                              omap4-wakeupgen.o

-AFLAGS_omap44xx-smc.o :=-Wa,-march=armv7-a
-
+plus_sec := $(call as-instr,.arch_extension sec,+sec)
+AFLAGS_omap-headsmp.o :=-Wa,-march=armv7-a$(plus_sec)
+AFLAGS_omap44xx-smc.o :=-Wa,-march=armv7-a$(plus_sec)
+
 # Functions loaded to SRAM
 obj-$(CONFIG_ARCH_OMAP2420) += sram242x.o
 obj-$(CONFIG_ARCH_OMAP2430) += sram243x.o
@@ -69,6 +71,7 @@ obj-$(CONFIG_OMAP_SMARTREFLEX_CLASS1P5) += smartreflex-class1p5.o

 AFLAGS_sleep24xx.o :=-Wa,-march=armv6
 AFLAGS_sleep34xx.o :=-Wa,-march=armv7-a
+AFLAGS_sleep44xx.o :=-Wa,-march=armv7-a$(plus_sec)

 ifeq ($(CONFIG_PM_VERBOSE),y)
 CFLAGS_pm_bus.o += -DDEBUG
diff --git a/security/smc/omap4/Makefile b/security/smc/omap4/Makefile
index af345a1..af545a2 100644
--- a/security/smc/omap4/Makefile
+++ b/security/smc/omap4/Makefile
@@ -38,4 +38,7 @@ tf_driver-objs += tf_comm_mshield.o
 tf_driver-objs += tf_device_mshield.o
 tf_driver-objs += bridge_pub2sec.o

+plus_sec := $(call as-instr,.arch_extension sec,+sec)
+AFLAGS_bridge_pub2sec.o :=-Wa,-march=armv7-a$(plus_sec)
+
 obj-$(CONFIG_SECURITY_MIDDLEWARE_COMPONENT) += tf_driver.o

This was already fixed on the latest kernels, refer to this thread for details. If you are using CodeSourcery toolchain referred in OMAPpedia wiki - you don't need it.
Compile the kernel with pandaboard defconfig (as per latest available L27.12.1-P2 release notes) with modified toolchain


  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- distclean
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- android_4430_defconfig
  make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- uImage

Later we will need to follow full instructions - patches, folders, environment variables, but to start working with kernel this should be pretty enough.

3. Download and install Eclipse
I prefer not to use one that is supplied with Ubuntu so I am just downloading Eclipse IDE for C/C++ Linux Developers 64-bit  from eclipse.org. Prefer to keep it in the opt folder usually...

  cd /opt
  sudo mkdir eclipse
  sudo chmod a+rwx eclipse
  tar -xvzf ~/Downloads/eclipse-linuxtools-indigo-incubation-linux-gtk-x86_64.tar.gz 

There is an ugly bug in the latest eclipse when it crashes during index rebuilding so I had to use a workaround offered by Marc-Andre Laperle with adding
  -XX:-UseCompressedOops
to eclipse.ini file. Probably I will also need to increase the maximum memory usage limitations later.

4. Configuring Eclipse to work with Linux kernel
Some time ago I used to use one python script to generate kernel symbols for the .project file, but today I have found a very nice article on how to correctly index kernel with Eclipse on the eclipse.org wiki. My customizations:

• Step 14: since we are doing cross compilation, I need to add custom build variables in the corresponding menu of the C/C++ Build options. Add ARCH with value arm and CROSS_COMPILE with value arm-linux-gnueabi- to all configurations. Maybe I will need to add some compiler options later here, but for now it is quite enough
• Step 15: use arm-linux-gnueabi-gcc for compiler command
• Step 25: here I have arch/arm/include, also I had to add arch/arm/plat-omap/include and arch/arm/mach-omap2/include
• Step 33: here I have everything except arch/arm
• Additionally in C/C++ Build options I am setting Build target in the Behavior tab to uImage and Build command in the Builder Settings tab to make ARCH=${ARCH} CROSS_COMPILE=${CROSS_COMPILE}
• In the end you will need to clean and rebuild from Eclipse to get the list of issues 

Your Eclipse is ready to work with OMAP4 2.6.35 Android kernel code. Enjoy...