31. Development Kit Root Makefile Help

The DPDK provides a root level Makefile with targets for configuration, building, cleaning, testing, installation and others. These targets are explained in the following sections.

31.1. Configuration Targets

The configuration target requires the name of the target, which is specified using T=mytarget and it is mandatory. The list of available targets are in $(RTE_SDK)/config (remove the defconfig _ prefix).

Configuration targets also support the specification of the name of the output directory, using O=mybuilddir. This is an optional parameter, the default output directory is build.

Config

This will create a build directory, and generates a configuration from a template. A Makefile is also created in the new build directory.

Example:
```
make config O=mybuild T=x86_64-native-linuxapp-gcc
```

31.2. Build Targets

Build targets support the optional specification of the name of the output directory, using O=mybuilddir. The default output directory is build.

all, build or just make

Build the DPDK in the output directory previously created by a make config.

Example:
```
make O=mybuild
```
clean

Clean all objects created using make build.

Example:
```
make clean O=mybuild
```
%_sub

Build a subdirectory only, without managing dependencies on other directories.

Example:
```
make lib/librte_eal_sub O=mybuild
```
%_clean

Clean a subdirectory only.

Example:
```
make lib/librte_eal_clean O=mybuild
```

31.3. Install Targets

Install

The list of available targets are in $(RTE_SDK)/config (remove the defconfig_ prefix).

The GNU standards variables may be used: http://gnu.org/prep/standards/html_node/Directory-Variables.html and http://gnu.org/prep/standards/html_node/DESTDIR.html

Example:
```
make install DESTDIR=myinstall prefix=/usr
```

31.4. Test Targets

test

Launch automatic tests for a build directory specified using O=mybuilddir. It is optional, the default output directory is build.

Example:
```
make test O=mybuild
```

31.5. Documentation Targets

doc

Generate the documentation (API and guides).
doc-api-html

Generate the Doxygen API documentation in html.
doc-guides-html

Generate the guides documentation in html.
doc-guides-pdf

Generate the guides documentation in pdf.

31.6. Deps Targets

depdirs

This target is implicitly called by make config. Typically, there is no need for a user to call it, except if DEPDIRS-y variables have been updated in Makefiles. It will generate the file $(RTE_OUTPUT)/.depdirs.

Example:
```
make depdirs O=mybuild
```
depgraph

This command generates a dot graph of dependencies. It can be displayed to debug circular dependency issues, or just to understand the dependencies.

Example:
```
make depgraph O=mybuild > /tmp/graph.dot && dotty /tmp/ graph.dot
```

31.7. Misc Targets

help

Show a quick help.

31.8. Other Useful Command-line Variables

The following variables can be specified on the command line:

V=

Enable verbose build (show full compilation command line, and some intermediate commands).
D=

Enable dependency debugging. This provides some useful information about why a target is built or not.
EXTRA_CFLAGS=, EXTRA_LDFLAGS=, EXTRA_LDLIBS=, EXTRA_ASFLAGS=, EXTRA_CPPFLAGS=

Append specific compilation, link or asm flags.
CROSS=

Specify a cross toolchain header that will prefix all gcc/binutils applications. This only works when using gcc.

31.9. Make in a Build Directory

All targets described above are called from the SDK root $(RTE_SDK). It is possible to run the same Makefile targets inside the build directory. For instance, the following command:

cd $(RTE_SDK)
make config O=mybuild T=x86_64-native-linuxapp-gcc
make O=mybuild

is equivalent to:

cd $(RTE_SDK)
make config O=mybuild T=x86_64-native-linuxapp-gcc
cd mybuild

# no need to specify O= now
make

31.10. Compiling for Debug

To compile the DPDK and sample applications with debugging information included and the optimization level set to 0, the EXTRA_CFLAGS environment variable should be set before compiling as follows:

export EXTRA_CFLAGS='-O0 -g'