To build the toolchain, simply type:

ct-ng build

This will use the above configuration to retrieve, extract and patch the components, build, install and eventually test your newly built toolchain. If all goes well, you should see something like this:

[INFO ]  Performing some trivial sanity checks
[INFO ]  Build started 20170319.002217
[INFO ]  Building environment variables
[EXTRA]  Preparing working directories
[EXTRA]  Installing user-supplied crosstool-NG configuration
[EXTRA]  =================================================================
[EXTRA]  Dumping internal crosstool-NG configuration
[EXTRA]    Building a toolchain for:
[EXTRA]      build  = x86_64-pc-linux-gnu
[EXTRA]      host   = x86_64-pc-linux-gnu
[EXTRA]      target = mipsel-sde-elf
[EXTRA]  Dumping internal crosstool-NG configuration: done in 0.05s (at 00:02)
[INFO ]  =================================================================
[INFO ]  Retrieving needed toolchain components' tarballs
[EXTRA]    Retrieving 'gmp-6.1.2'
[EXTRA]    Saving 'gmp-6.1.2.tar.xz' to local storage
[EXTRA]    Retrieving 'mpfr-3.1.5'
[EXTRA]    Saving 'mpfr-3.1.5.tar.xz' to local storage
[INFO ]  Installing cross-gdb
[EXTRA]    Configuring cross-gdb
[EXTRA]    Building cross-gdb
[EXTRA]    Installing cross-gdb
[EXTRA]    Installing '.gdbinit' template
[INFO ]  Installing cross-gdb: done in 98.55s (at 10:51)
[INFO ]  =================================================================
[INFO ]  Cleaning-up the toolchain's directory
[INFO ]    Stripping all toolchain executables
[EXTRA]    Creating toolchain aliases
[EXTRA]    Removing access to the build system tools
[EXTRA]    Removing installed documentation
[INFO ]  Cleaning-up the toolchain's directory: done in 0.42s (at 10:52)
[INFO ]  Build completed at 20170319.003309
[INFO ]  (elapsed: 10:51.42)
[INFO ]  Finishing installation (may take a few seconds)...

You are then free to add the toolchain’s /bin directory in your PATH to use it at will.

Stopping and restarting a build

If you want to stop the build after a step you are debugging, you can pass the variable STOP to make:

ct-ng build STOP=some_step

Conversely, if you want to restart a build at a specific step you are debugging, you can pass the RESTART variable to make:

ct-ng build RESTART=some_step

Alternatively, you can call make with the name of a step to just do that step:

ct-ng libc_headers

which is equivalent to:

ct-ng build RESTART=libc_headers STOP=libc_headers

The shortcuts +step_name and step_name+ allow to respectively stop or restart at that step. Thus

ct-ng +libc_headers

is equivalent to

ct-ng build STOP=libc_headers


ct-ng libc_headers+

is equivalent to:

ct-ng build RESTART=libc_headers

To obtain the list of acceptable steps, please call:

ct-ng list-steps

Note that in order to restart a build, you’ll have to say Y to the config option CT_DEBUG_CT_SAVE_STEPS, and that the previous build effectively went that far.

Overriding the number of jobs

If you want to override the number of jobs to run in (the -j option to make), you can either re-enter the menuconfig, or simply add it on the command line, as such:

ct-ng build.4

which tells crosstool-NG to override the number of jobs to 4.

You can see the actions that support overriding the number of jobs in the help menu. Those are the ones with [.#] after them (e.g., build[.#] or build-all[.#], and so on).


The crosstool-NG script ct-ng is a Makefile-script. It does not execute in parallel (there is not much to gain). When speaking of jobs, we are refering to the number of jobs when making the components. That is, we speak of the number of jobs used to build gcc, glibc, and so on.

Building all toolchains at once

You can build all samples; simply call:

ct-ng build-all

Note that it is very time consuming (depending on your machine configuration and host OS, it takes from 24 hours to a full week). By default, this removes each build tree after a successful build, but leaves the unpacked/patched sources so that they can be re-used by the samples that follow). However, even that consumes considerable amount of disk space given the variety of component versions represented in samples.