Before this commit, weak symbols were not overridden by non-weak symbols
found in archive libraries when linking with recent versions of
binutils. As stated in the System V ABI, "the link editor does not
extract archive members to resolve undefined weak symbols".
This commit changes all Makefiles to use partial linking (ld -r) instead
of creating library archives, which forces all symbols to participate in
linking, allowing non-weak symbols to override weak symbols as intended.
This approach is also used by Linux, from which the gmake function
cmd_link_o_target (defined in config.mk and used in all Makefiles) is
inspired.
The name of each former library archive is preserved except for
extensions which change from ".a" to ".o". This commit updates
references accordingly where needed, in particular in some linker
scripts.
This commit reveals board configurations that exclude some features but
include source files that depend these disabled features in the build,
resulting in undefined symbols. Known such cases include:
- disabling CMD_NET but not CMD_NFS;
- enabling CONFIG_OF_LIBFDT but not CONFIG_QE.
Signed-off-by: Sebastien Carlier <sebastien.carlier@gmail.com>
Modifications are based on the linux kernel approach and
support two use cases:
1) Add O= to the make command line
'make O=/tmp/build all'
2) Set environement variable BUILD_DIR to point to the desired location
'export BUILD_DIR=/tmp/build'
'make'
The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'
Command line 'O=' setting overrides BUILD_DIR environent variable.
When none of the above methods is used the local build is performed and
the object files are placed in the source directory.
Notes:
- Board-dependend code for RPXLITE and RPXCLASSIC-based boards
placed to the drivers/rpx_pmcia.c file to avoid duplication.
Same for TQM8xx-based boards (drivers/tqm8xx_pmcia.c).
- drivers/i82365.c has been split into two parts located at
board/atc/ti113x.c and board/cpc45/pd67290.c (ATC and CPC45 are
the only boards using CONFIG_82365).
- Changes were tested for clean build and *very* *few* boards.
Using external watchdog for KUP4 boards in mpc8xx/cpu.c;
load_sernum_ethaddr() for KUP4 boards in lib_ppc/board.c;
various changes to KUP4 board specific files
