Compile - compile for itop4412 development board makefile

In front of the introductory video, issue 10 “ Build a compilation environment uboot_linux_Android” in , Only the input is described Make Command to compile the kernel , It doesn't show how it works . This is done when adding drivers to the kernel 3 Work , Include ：

1） stay Kconfig Add the new code to the compilation conditions of the project , This part of the experiment 3 It has been introduced ;

2） Add the driver source code to the corresponding directory , This step is easier to understand , In this chapter, we will show you ;

3） In the catalog Makefile Add a compile entry for the new code in the , This part will introduce in this chapter . Video resources ：

The supporting video of this section is “ video 04_Makefile compile ” 

1 Compiler path settings

In the previous introductory knowledge , It only introduces the directory in which to decompress the compiler , Add a path to the environment variable file , You can compile the kernel , It doesn't explain how they correspond to each other .

As shown in the figure below , Follow the basic tutorial provided earlier , Good configuration Ubuntu Compiler and library files in , Enter the command “make”, You can compile and generate a binary image of the kernel .

As shown in the figure below , Use command “#cd”, Use command “#vim .bashrc” Open environment variable file “.bashrc”.

As shown in the figure below , Go to bottom line , You can see , In the environment variable file, the compiler path is set to

export PATH=$PATH:/usr/local/arm/arm-2009q3/bin

Then use the command “#cd /usr/local/arm/”, Enter the decompression compiler “arm-2009q3.tar.bz2” File directory for

You can see clearly , The path set in the environment variable corresponds to the path of decompression . Back to the kernel source code directory , As shown in the figure below .

As shown in the figure below , Use command “vim Makefile” Open the kernel directory Makefile file .

Through here vim The editor looks for parameters “CROSS_COMPILE”, As shown in the figure below .

You can find the parameters “CROSS_COMPILE”, As shown in the figure below .

Let's look at the parameters again “CROSS_COMPILE” Next line , You can see that there are traces of changes here . It's easy to infer that , It turns out that Samsung uses “4.5.1” Version of compiler , But it doesn't matter , As long as it can be compiled and passed .

As a general rule , The first step after getting the source code , It is necessary to compile the source code first . Set the variables in the figure above “CROSS_COMPILE” And the environment variables and the compiler's actual decompression path . After these three correspond , To ensure that Make After the command , The system can find the compiler .

During the execution of the compile command , Will prompt some mistakes , And then according to the error in the prompt , Check and revise one by one , To add or modify library files . There are advantages and disadvantages in this process , The test is only patience , Not too much skill . Since the missing library files have been written into scripts , In this way, you can compile the following script in the compiler .

In the kernel directory Makefile file , Let me remind you , There is a lot in this document , With the exception of the compiler path variables above, little attention is paid to .

There is another place to learn about , As shown in the figure below , In the first line of the file , You can see the version of the kernel .