Using External Toolchains

If an external toolchain is used then a number of Buildroot options must be configured properly, since Buildroot cannot detected all available toolchain's features itself. This guide describes how to properly configure an external toolchain.

Selecting an External Toolchain

By default, Buildroot builds a Linux toolchain for ARC from scratch and may use relatively old sources for tools like GCC, Binutils, etc. If you want to use the latest available toolchain for ARC processors, then consider using prebuilt components from the official releases page.

Here is an example of how you can select the external toolchain for ARC HS3x/4x targets based on glibc:

Toolchain -> Toolchain type -> (X) External toolchain
          -> (X) Custom toolchain
          -> Toolchain origin -> (X) Toolchain to be downloaded and installed
          -> Toolchain URL -> <Your .tar.gz url from GitHub>

If the toolchain is already downloaded in installed then you can pick it up this way:

Toolchain -> Toolchain type -> (X) External toolchain
          -> (X) Custom toolchain
          -> Toolchain origin -> (X) Pre-installed toolchain
          -> Toolchain path -> /tools/toolchains/arc-linux-gnu

Kernel Headers Version

All Linux toolchains are shipped with Linux headers for a particular Linux kernel version. You can configure it this way:

Toolchain -> External toolchain kernel headers series -> <version>

This option corresponds to BR2_TOOLCHAIN_EXTERNAL_HEADERS_<major>_<minor>=y configuration line, where <major> stands for a major version and <minor> stands for a minor version. For example, if the Linux kernel's version is 5.16 then 5.16.x value must be selected in the configuration menu of BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y configuration line must be added.

Here is a table of kernel versions for different toolchain releases:

Toolchain release	Linux headers version
2024.06 — 2022.09	5.16
2021.09 — 2021.03	5.1
2020.09	5.7
2020.03 — 2018.03	4.15
2017.09	4.12
2017.03	4.9
2016.09	4.8
2016.03	4.6
2015.12 — 2015.06	3.18
earlier	3.13

Options for 2024.06 Toolchain Release

Note

RPC support must be explicitly disabled since Buildroot configurator may enable it by default.

Release 2024.06 for HS6x Family (glibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 14.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> glibc
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_14=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2024.06 for HS5x Family (uClibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 14.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_14=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y

Release 2024.06 for HS3x/4x Families (glibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 14.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> glibc
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_14=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2024.06 for HS3x/4x Families (uClibc-based)

Additional options for uClibc-based toolchain:

Toolchain -> External toolchain gcc version -> 14.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_14=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2024.06 for ARC700 Family (uClibc-based)

Additional options for uClibc-based toolchain:

Toolchain -> External toolchain gcc version -> 14.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_14=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y

Options for 2023.09 Toolchain Release

Note

RPC support must be explicitly disabled since Buildroot configurator may enable it by default.

Release 2023.09 for HS6x Family (glibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 13.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> glibc
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_13=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2023.09 for HS5x Family (uClibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 13.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_13=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y

Release 2023.09 for HS3x/4x Families (glibc-based)

Additional options for the toolchain:

Toolchain -> External toolchain gcc version -> 13.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> glibc
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_13=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2023.09 for HS3x/4x Families (uClibc-based)

Additional options for uClibc-based toolchain:

Toolchain -> External toolchain gcc version -> 13.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?
             [*] Toolchain has Fortran support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_13=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_FORTRAN=y

Release 2023.09 for ARC700 Family (uClibc-based)

Additional options for uClibc-based toolchain:

Toolchain -> External toolchain gcc version -> 13.x
             External toolchain kernel headers series -> 5.16.x
             External toolchain C library -> uClibc/uClibc-ng
             [*] Toolchain has WCHAR support?
             [*] Toolchain has SSP support?
             [ ] Toolchain has RPC support?
             [*] Toolchain has C++ support?

Configuration file lines:

BR2_TOOLCHAIN_EXTERNAL_GCC_13=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_5_16=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_UCLIBC=y
BR2_TOOLCHAIN_EXTERNAL_WCHAR=y
BR2_TOOLCHAIN_EXTERNAL_HAS_SSP=y
BR2_TOOLCHAIN_EXTERNAL_INET_RPC=n
BR2_TOOLCHAIN_EXTERNAL_CXX=y