toolchain-external: align library locations in target and staging dir

The toolchain-external logic is roughly:
- populate the staging dir by rsyncing the entire ${ARCH_LIB_DIR} and
  usr/${ARCH_LIB_DIR} from sysroot.
- populate the target dir by explictly copying some libraries from sysroot
  into target/lib and some other libraries in target/usr/lib, the split
  being hardcoded into buildroot regardless of the location in the sysroot.

This means that a library libfoo could be located in:
  staging/lib/libfoo.so
  target/usr/lib/libfoo.so

When debugging an application that links against this library, gdb will
fruitlessly search for 'usr/lib/libfoo.so' in staging, and then suggest to
use 'set solib-search-path' which is a hack, really.

To solve the problem, we need to make sure that libraries from the toolchain
are installed in the same relative location in staging and target.
Achieve this by:
- replacing the convoluted search for libraries using for+find in sysroot
  with a simple find in staging.
- determining DESTDIR for each library individually based on the location in
  staging.
- treating LIB_EXTERNAL_LIBS and USR_LIB_EXTERNAL_LIBS equivalently

These changes also allow for the removal of most arguments to
copy_toolchain_lib_root in the method itself and their callers.

Test procedure:
- set configuration for a given toolchain
- make clean toolchain
- find output/target | sort > /tmp/out-before
- apply patch
- make clean toolchain
- find output/target | sort > /tmp/out-after
- diff -u /tmp/out-before /tmp/out-after

The only changes should be some libraries moving from lib to usr/lib or vice
versa. Notable examples being libstdc++ and libatomic.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas:
 - use -L instead of -follow in the find invocation, as suggested by
   Arnout.
 - move the BR2_STATIC_LIBS condition as a make condition rather than
   a shell condition, as suggested by Arnout.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

1 files changed, 5 insertions, 52 deletions

diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
index ee878e89a1..eeac7d2f29 100644
--- a/toolchain/helpers.mk
+++ b/toolchain/helpers.mk
@@ -6,62 +6,15 @@
 # toolchain logic, and the glibc package, so care must be taken when
 # changing this function.
 #
-# Most toolchains (CodeSourcery ones) have their libraries either in
-# /lib or /usr/lib relative to their ARCH_SYSROOT_DIR, so we search
-# libraries in:
-#
-#  $${ARCH_LIB_DIR}
-#  usr/$${ARCH_LIB_DIR}
-#
-# Buildroot toolchains, however, have basic libraries in /lib, and
-# libstdc++/libgcc_s in /usr/<target-name>/lib(64), so we also need to
-# search libraries in:
-#
-#  usr/$(TOOLCHAIN_EXTERNAL_PREFIX)/$${ARCH_LIB_DIR}
-#
-# Linaro toolchains have most libraries in lib/<target-name>/, so we
-# need to search libraries in:
-#
-#  $${ARCH_LIB_DIR}/$(TOOLCHAIN_EXTERNAL_PREFIX)
-#
-# And recent Linaro toolchains have the GCC support libraries
-# (libstdc++, libgcc_s, etc.) into a separate directory, outside of
-# the sysroot, that we called the "SUPPORT_LIB_DIR", into which we
-# need to search as well.
-#
-# Thanks to ARCH_LIB_DIR we also take into account toolchains that
-# have the libraries in lib64 and usr/lib64.
-#
-# Please be very careful to check the major toolchain sources:
-# Buildroot, Crosstool-NG, CodeSourcery and Linaro before doing any
-# modification on the below logic.
-#
-# $1: arch specific sysroot directory
-# $2: support libraries directory (can be empty)
-# $3: library directory ('lib' or 'lib64') from which libraries must be copied
-# $4: library name
-# $5: destination directory of the libary, relative to $(TARGET_DIR)
+# $1: library name
 #
 copy_toolchain_lib_root = \
-	ARCH_SYSROOT_DIR="$(strip $1)"; \
-	SUPPORT_LIB_DIR="$(strip $2)" ; \
-	ARCH_LIB_DIR="$(strip $3)" ; \
-	LIB="$(strip $4)"; \
-	DESTDIR="$(strip $5)" ; \
+	LIB="$(strip $1)"; \
 \
-	for dir in \
-		$${ARCH_SYSROOT_DIR}/$${ARCH_LIB_DIR}/$(TOOLCHAIN_EXTERNAL_PREFIX) \
-		$${ARCH_SYSROOT_DIR}/usr/$(TOOLCHAIN_EXTERNAL_PREFIX)/$${ARCH_LIB_DIR} \
-		$${ARCH_SYSROOT_DIR}/$${ARCH_LIB_DIR} \
-		$${ARCH_SYSROOT_DIR}/usr/$${ARCH_LIB_DIR} \
-		$${SUPPORT_LIB_DIR} ; do \
-		LIBPATHS=`find $${dir} -maxdepth 1 -name "$${LIB}" 2>/dev/null` ; \
-		if test -n "$${LIBPATHS}" ; then \
-			break ; \
-		fi \
-	done ; \
-	mkdir -p $(TARGET_DIR)/$${DESTDIR}; \
+	LIBPATHS=`find -L $(STAGING_DIR) -name "$${LIB}" 2>/dev/null` ; \
 	for LIBPATH in $${LIBPATHS} ; do \
+		DESTDIR=`echo $${LIBPATH} | sed "s,^$(STAGING_DIR)/,," | xargs dirname` ; \
+		mkdir -p $(TARGET_DIR)/$${DESTDIR}; \
 		while true ; do \
 			LIBNAME=`basename $${LIBPATH}`; \
 			LIBDIR=`dirname $${LIBPATH}` ; \