Compile Device Driver for Linux in Eclipse

There is an easy way to compile device driver in Linux using eclipse, once its been setup life becomes much easy, as you don't have to switch between the editor and the command shell every time you need to change something,

Here is the screen shot of my project, Look at it carefully, all you need to add to the project are main.c and a makefile. rest are the result of compilation. makefile will only contain one line obj-m := main.o

Most of the things remain same for the simple C project as mentioned in the previous post, after creating the project, you need to change the command to build the project as,

make -C /usr/src/linux-headers-2.6.35-22-generic M=$(PWD) modules

The path given above is my linux kernel header file path, change to yours accordingly. After this, you set the build directory to the directory of your source code for device drivers. And in the behavior tab, remove the all from build command line, other wise it will crib saying could not find rule to build all !! 

Thats it, you are ready to use the Eclipse IDE for device driver development, all the best !

Compiling Linux Kernel in eclipse, and debugging using QEMU

After I have started working with this eclipse IDE, I came across an article in a blog, and found it very interesting. The fact that compiling Linux kernel is fairly easy on the terminal does not need it to be compiled somewhere else, but then the fact that once configured, if you are using eclipse as an IDE for modifying and browsing the source code, it would be beneficial if you can directly build from there.

The procedure is very simple in fact !

Download the latest version of kernel from kernel.org website (ftp) and extract it to where ever you want to. The latest version now is (2.6.36.2), so download the linux-2.6.36.2.tar.gz file from ftp, and copy it to you home directory (in my case prasad)

tar xzvf linux-2.6.36.2.tar.gz

Now build the kernel, after configuring, and make sure it builds fine when built from the command prompt. Now its easy to integrate this environment into eclipse, this is almost same my previous post of building a make file based c project to build in eclipse. But it just looks complicated because its kernel.

Create a new make file based C project ans select the kernel source directory to be your project directory and select other tool chain option for tool chain. Click finish, I hope you have disabled indexing and auto build. 

Now, go to project properties and update the build directory path, and build command as needed, if you are building kernel in the same directory as the source code, you don't have to change anything here, but in case out put directory is different then just update the command as make O=/build/linux-2.6-xxx and build directory to /build/linux-2.6-xxx.

If you were building for a different target other than x86, update the Makefile of linux kernel with the CROSS_COMPILE and ARCH, or you can as well give them in the make command also.

Now click build all, you can see that eclipse IDE runs the commands set and outputs of the compilations are seen on eclipse console. if there is any error, you can just double click and the corresponding source code is highlighted (this is the best part of using an IDE)

Now you are ready to connect to QEMU for debugging the kernel, locate you bzImage/zImage, (kernel binary), run the kernel in QEMU, refer to qemu manual for how to do that (!?)

for your reference, in case of x86 kernel to be run on the QEMU type in this command (I assume qemu is compiled and installed)

qemu -hda /dev/zero -kernel ~/linux-2.6.32.2/arch/i386/boot/bzImage -s -S

-s -S options make the qemu wait on the TCP connection at port 1234 for the gdb debugger to connect. 

Now in the eclipse IDE, go to Run->Debug Configurations, double click on C/C++ application, a new configuration will be created. Browse the project, and in C/C++ application field browse the vmlinux for your kernel, and set the path for it. In the debugger tab, select the gdb-server, and set the stop point to be start_kernel. In the connections tab, set it to TCP and 1234 port number, and you are ready for debugging. 

The whole thing is explained in detail in the blog post here, Thanks for the wonderful information, it was really helpful for me. I myself debugged kernel using this approach in eclipse, if anybody faced problem let me know, I am glad to help you out.

Compile C/C++ code in eclipse using makefiles

In Linux, usually compilation is done using makefiles, run in command shell. I use to work on Linux kernel, and in such cases, I use to setup a Samba server for editing and source code browsing was done in windows. But then now I am using only one PC, which is a dual boot for windows and Ubuntu Linux, so I cannot have samba server. I was looking for a IDE in Linux, and found eclipse to be very useful.

I wasn't very familiar with the eclipse IDE and I was trying to setup the compilation using makefiles, initially I had some hiccups but could later configure it easily after generating an example C project from it and following similar methods to write the makefiles.

Here is the method to do it, so it might come handy to you in case if you are trying to use eclipse IDE for compiling C/C++ project using make files.

First create a empty C/C++ project, makefile project, and select the --other tool chain--. keep the project settings to default, as shown in the below figure. Click finish.

Once project is created, as a C file, and a 'makefile'. The makefile tells the make program about how the project should be built, I am giving here the sample make file for the simple HelloWorld.c, which you can further extend as per your use.