This patchset allows to build host programs that depend on external libs
installed in non standard locations (i.e. not in /usr/include, /usr/lib,
etc.).  For now, the only way is to force HOSTCC to include both the
path to the host compiler and the build flags.

I have encountered this issue when building linux into the buildroot
framework. host-* versions of libs may be compiled and installed in a
host staging dir removing the need to install them on the build system.

I'm not really satisfied with the new HOST_{C,LD}FLAGS variables.  They
are too similar to HOST{C,LD}FLAGS and I find them confusing.  However,
HOST_EXTRA*FLAGS are already reserved for local use in makefiles (see
Documentation/kbuild/makefiles.txt).  And I didn't want to have even
longer USER_HOST_*FLAGS.  If someone has a better proposition, I'll
happily make a v3.

Comments are welcome.

Changes since v1:
 - Fix typos.
 - Do not use HOST_EXTRA*FLAGS. Add new user specifiable variables.
 - Pass HOSTLDFLAGS to build single .c programs.
 - Build objtool with host flags.

Robin Jarry (3):
  kbuild: introduce HOST_{C,LD}FLAGS
  kbuild: use HOSTLDFLAGS for single .c executables
  objtool: use global host flags for compilation

 Documentation/admin-guide/README.rst | 16 ++++++++++++++++
 Makefile                             |  9 +++++----
 scripts/Makefile.host                |  2 +-
 tools/objtool/Makefile               |  4 ++--
 4 files changed, 24 insertions(+), 7 deletions(-)

-- 
2.11.0