Big patch form Ralf Corsepius described in this email:

  Here is the result of my nightly work to get RTEMS_ROOT=$srcdir working
  with different shells and relative/absolute paths.

  What I did is relatively simple in principle:
  Instead of setting RTEMS_ROOT in configure.in and then let configure
  substitute @RTEMS_ROOT@ inside the Makefiles, I now let each Makefile
  set RTEMS_ROOT from each Makefile's @top_srcdir@ value.

  The difference is subtile, but with enormous side effects:
  - If RTEMS_ROOT is set in configure, then the same single value will be
  propagated to all Makefiles. This breaks using relative paths, as the
  relative path to the root of the source tree is used inside of all
  subdirectory Makefiles.
  - Now each Makefile.in sets RTEMS_ROOT = @top_srcdir@.  top_srcdir  is
  computed individually by configure for each single Makefile.in, hereby
  receiving the correct value, no matter if relative or absolute paths are
  used.

  To get this working, I needed to remove setting RTEMS_ROOT from
  target.cfg.in, because this overrides the value of RTEMS_ROOT from each
  individual Makefile.


  Furthermore, I removed RTEMS_CUSTOM from the Makefiles and replaced all
  "include $(RTEMS_CUSTOM)" directives with"include
  $(RTEMS_ROOT)/make/custom/$(RTEMS_BSP)". Perhaps you don't like this,
  but I think, to have one variable less is clearer and easier to
  understand than having several variables refering to the next one.


  I enclose a small patch to this mail, which
  - fixes the config.h problem (to finally clearify misunderstands)
  - removes assignment/subsitution of RTEMS_ROOT from configure.in
  - contains a workaround for the application Makefile's RTEMS_ROOT
  problem (reported by Eric)
  - removes some unused lines from the toplevel Makefile.in
  - removes assignment of RTEMS_ROOT from make/target.cfg.in

1 files changed, 2 insertions, 4 deletions

diff --git a/c/src/librtems++/src/Makefile.in b/c/src/librtems++/src/Makefile.in
index 0e1903d461..c69c34790a 100644
--- a/c/src/librtems++/src/Makefile.in
+++ b/c/src/librtems++/src/Makefile.in
@@ -4,11 +4,9 @@
 
 @SET_MAKE@
 srcdir = @srcdir@
-top_srcdir = @top_srcdir@
 VPATH = @srcdir@
-RTEMS_ROOT = @RTEMS_ROOT@
+RTEMS_ROOT = @top_srcdir@
 PROJECT_ROOT = @PROJECT_ROOT@
-RTEMS_CUSTOM = $(RTEMS_ROOT)/make/custom/$(RTEMS_BSP).cfg
 
 LIBNAME=librtems++.a
 LIB=${ARCH}/${LIBNAME}
@@ -22,7 +20,7 @@ CC_O_FILES=$(CC_PIECES:%=${ARCH}/%.o)
 SRCS=$(CC_FILES)
 OBJS=$(CC_O_FILES)
 
-include $(RTEMS_CUSTOM)
+include $(RTEMS_ROOT)/make/custom/$(RTEMS_BSP).cfg
 include $(RTEMS_ROOT)/make/lib.cfg
 
 #