# Compilation and Installation using Autoconf

1. Basic Usage

2. Driver Options

   - Xlib Driver Options
   - DRI Driver Options
   - OSMesa Driver Options

3. Demo Program Options

## 1. Basic Usage

The autoconf generated configure script can be used to guess your platform and change various options for building Mesa. To use the configure script, type:

        ./configure

To see a short description of all the options, type `./configure --help`. If you are using a development snapshot and the configure script does not exist, type `./autogen.sh` to generate it first. If you know the options you want to pass to `configure`, you can pass them to `autogen.sh`. It will run `configure` with these options after it is generated. Once you have run `configure` and set the options to your preference, type:

        make

This will produce libGL.so and several other libraries depending on the options you have chosen. Later, if you want to rebuild for a different configuration run `make realclean` before rebuilding.

Some of the generic autoconf options are used with Mesa:

- `--prefix=PREFIX` - This is the root directory where files will be installed by `make install`. The default is `/usr/local`.
- `--exec-prefix=EPREFIX` - This is the root directory where architecture-dependent files will be installed. In Mesa, this is only used to derive the directory for the libraries. The default is `${prefix}`.
- `--libdir=LIBDIR` - This option specifies the directory where the GL libraries will be installed. The default is `${exec_prefix}/lib`. It also serves as the name of the library staging area in the source tree. For instance, if the option `--libdir=/usr/local/lib64` is used, the libraries will be created in a `lib64` directory at the top of the Mesa source tree.
- `--enable-static, --disable-shared` - By default, Mesa will build shared libraries. Either of these options will force static libraries to be built. It is not currently possible to build static and shared libraries in a single pass.
- `CC, CFLAGS, CXX, CXXFLAGS` - These environment variables control the C and C++ compilers used during the build. By default, `gcc` and `g++` are used with the options `"-g -O2"`.
- `LDFLAGS` - An environment variable specifying flags to pass when linking programs. These are normally empty, but can be used to direct the linker to use libraries in nonstandard directories. For example, `LDFLAGS="-L/usr/X11R6/lib"`.
- `PKG_CONFIG_PATH` - When available, the `pkg-config` utility is used to search for external libraries on the system. This environment variable is used to control the search path for `pkg-config`. For instance, setting `PKG_CONFIG_PATH=/usr/X11R6/lib/pkgconfig` will search for package metadata in `/usr/X11R6` before the standard directories.

There are also a few general options for altering the Mesa build:

- `--with-x` - When the X11 development libraries are needed, the `pkg-config` utility will be used for locating them. If they cannot be found through `pkg-config` a fallback routing using `imake` will be used. In this case, the `--with-x`, `--x-includes` and `--x-libraries` options can control the use of X for Mesa.
- `--enable-gl-osmesa` - The OSMesa library can be built on top of libGL for drivers that provide it. This option controls whether to build libOSMesa. By default, this is enabled for the Xlib driver and disabled otherwise. Note that this option is different than using OSMesa as the driver.
- `--enable-debug` - This option will enable compiler options and macros to aid in debugging the Mesa libraries.
- `--disable-asm` - There are assembly routines available for a few architectures. These will be used by default if one of these architectures is detected. This option ensures that assembly will not be used.
- `--enable-32-bit, --enable-64-bit` - By default, the build will compile code as directed by the environment variables `CC`, `CFLAGS`, etc. If the compiler is `gcc`, these options offer a helper to add the compiler flags to force 32- or 64-bit code generation as used on the x86 and x86_64 architectures.

## 2. Driver Options

There are several different driver modes that Mesa can use. These are described in more detail in the basic installation instructions. The Mesa driver is controlled through the configure option --with-driver. There are currently three supported options in the configure script.

### Xlib

This is the default mode for building Mesa. It uses Xlib as a software renderer to do all rendering. It corresponds to the option `--with-driver=xlib`. The libX11 and libXext libraries, as well as the X11 development headers, will be need to support the Xlib driver.

### DRI

This mode uses the DRI hardware drivers for accelerated OpenGL rendering. Enable the DRI drivers with the option `--with-driver=dri`. See the basic installation instructions for details on prerequisites for the DRI drivers.

`--with-dri-driverdir=DIR`

  This option specifies the location the DRI drivers will be installed to and the location libGL will search for DRI drivers. The default is `${libdir}/dri`.

`--with-dri-drivers=DRIVER,DRIVER,...`

  This option allows a specific set of DRI drivers to be built. For example, `--with-dri-drivers="swrast,i965,radeon,nouveau"`. By default, the drivers will be chosen depending on the target platform. See the directory `src/mesa/drivers/dri` in the source tree for available drivers. Beware that the swrast DRI driver is used by both libGL and the X.Org xserver GLX module to do software rendering, so you may run into problems if it is not available.

`--disable-driglx-direct`

  Disable direct rendering in GLX. Normally, direct hardware rendering through the DRI drivers and indirect software rendering are enabled in GLX. This option disables direct rendering entirely. It can be useful on architectures where kernel DRM modules are not available.

`--enable-glx-tls`

  Enable Thread Local Storage (TLS) in GLX.

`--with-expat=DIR`
  The DRI-enabled libGL uses expat to parse the DRI configuration files in `/etc/drirc` and `~/.drirc`. This option allows a specific expat installation to be used. For example, `--with-expat=/usr/local` will search for expat headers and libraries in `/usr/local/include` and `/usr/local/lib`, respectively.

### OSMesa

No libGL is built in this mode. Instead, the driver code is built into the Off-Screen Mesa (OSMesa) library. See the Off-Screen Rendering page for more details.

`--with-osmesa-bits=BITS`

  This option allows the size of the color channel in bits to be specified. By default, an 8-bit channel will be used, and the driver will be named libOSMesa. Other options are 16- and 32-bit color channels, which will add the bit size to the library name. For example, `--with-osmesa-bits=16` will create the libOSMesa16 library with a 16-bit color channel.

## 3. Library Options

The configure script provides more fine grained control over the GL libraries that will be built. More details on the specific GL libraries can be found in the basic installation instructions.

## 4. Demo Program Options

There are many demonstration programs in the MesaDemos tarball. If the programs are available when `./configure` is run, a subset of the programs will be built depending on the driver and library options chosen. See the directory `progs` for the full set of demos.

`--with-demos=DEMOS,DEMOS,...`

  This option allows a specific set of demo programs to be built. For example, `--with-demos="xdemos,slang"`. Beware that if this option is used, it will not be ensured that the necessary GL libraries will be available.

`--without-demos`

  This completely disables building the demo programs. It is equivalent to `--with-demos=no`.