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:
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 |
|---|---|
| 2024.12 — 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 2024.12 Toolchain Release¶
Note
RPC support must be explicitly disabled since Buildroot configurator may enable it by default.
Options 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
Options 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
Options 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
Options 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
Options 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: