manual: improve documentation about using external toolchains

- Remove the redundant FAQ entry about this topic,
  already covered in a specific section of the Development Tasks manual

- Document the TOOLCHAIN_LOCATION variable

- Expand both the Development Tasks manual and
  the TCMODE variable description using details from the FAQ entry.

- Mention the "meta-arm-toolchain" layer too.

(From yocto-docs rev: 53faa54a8e6311b4d3d41d96cb1a497d0f6502fb)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 2 insertions, 17 deletions

diff --git a/documentation/ref-manual/faq.rst b/documentation/ref-manual/faq.rst
index 8f38808a78..a3a15506c3 100644
--- a/documentation/ref-manual/faq.rst
+++ b/documentation/ref-manual/faq.rst
@@ -168,23 +168,8 @@ Using the OpenEmbedded Build system
 How do I use an external toolchain?
 -----------------------------------
 
-The toolchain configuration is very flexible and customizable. It
-is primarily controlled with the :term:`TCMODE` variable. This variable
-controls which ``tcmode-*.inc`` file to include from the
-``meta/conf/distro/include`` directory within the :term:`Source Directory`.
-
-The default value of :term:`TCMODE` is "default", which tells the
-OpenEmbedded build system to use its internally built toolchain (i.e.
-``tcmode-default.inc``). However, other patterns are accepted. In
-particular, "external-\*" refers to external toolchains. One example is
-the Sourcery G++ Toolchain. The support for this toolchain resides in
-the separate ``meta-sourcery`` layer at
-https://github.com/MentorEmbedded/meta-sourcery/.
-
-In addition to the toolchain configuration, you also need a
-corresponding toolchain recipe file. This recipe file needs to package
-up any pre-built objects in the toolchain such as ``libgcc``,
-``libstdcc++``, any locales, and ``libc``.
+See the ":ref:`dev-manual/external-toolchain:optionally using an external toolchain`"
+section in the Development Task manual.
 
 Why do I get chmod permission issues?
 -------------------------------------