Signed-off-by: Tom Rini <trini@konsulko.com>

Signed-off-by: Tom Rini <trini@konsulko.com>

Some toolchains are compiled so that they pass a --build-id=something
parameter to the linker implicitly.

This causes U-Boot LTO linking to fail with something like:
  ld: section .note.gnu.build-id LMA ... overlaps section .text LMA ...
because U-Boot's link scripts do not currently handle .note.gnu.build-id
section.

Fix this by explicitly disabling build-id.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>

Add plumbing for building U-Boot with Link Time Optimizations.

When building with LTO, $(PLATFORM_LIBS) has to be in --whole-archive /
--no-whole-archive group, otherwise some functions declared in assembly
may not be resolved and linking may fail.

Note: clang may throw away linker list symbols it thinks are unused when
compiling with LTO. To force these symbols to be included, we refer to
them via the __ADDRESSABLE macro in a C file generated from compiled
built-in.o files before linking.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>

Currently we use incremental linking (ld -r) to link several object
files from one directory into one built-in.o object file containing the
linked code from that directory (and its subdirectories).

Linux has, some time ago, moved to thin archives instead.

Thin archives are archives (.a) that do not really contain the object
files, only references to them.

Using thin archives instead of incremental linking
- saves disk space
- apparently works better with dead code elimination
- makes things easier for LTO

The third point is the important one for us. With incremental linking
there are several options how to do LTO, and that would unnecessarily
complicate things.

We have to use the --whole-archive/--no-whole-archive linking option
instead of --start-group/--end-group, otherwise linking may fail because
of unresolved symbols, or the resulting binary will be unusable.

We also need to use the P flag for ar, otherwise final linking may fail.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>

Indent the linking commands so that they look cosmetically better.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

For scenarios like OF_BOARD or OF_PRIOR_STAGE, no device tree blob is
provided in the U-Boot build phase hence the binman node information
is not available. In order to support such use case, a new Kconfig
option BINMAN_STANDALONE_FDT is introduced, to tell the build system
that a device tree blob containing binman node is explicitly required
when using binman to package U-Boot.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

This updates the make rules to pass OpenSBI blob to binman.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Versions of U-Boot before 2014.01 created a symlink from include/asm to
the architecture-specific header directory.

If an ARM board is build with that old version, then sandbox is built on
a more recent version (both with in-tree builds), the include/asm symlink
confuses the build system. It picks up the ARM headers when it should be
using the sandbox ones.

Since 2014 U-Boot has only created a symlink inside the include/asm/
directory and only for out-of-tree builds. So for in-tree builds it does
not expect to see an include/asm symlink. It is not removed by
'make mrproper'. It does show up with 'git status' but is easy enough to
miss.

Add include/asm to the files to remove with 'make mkproper'. For recent
U-Boot builds this has no effect, since include/asm is a directory, not a
file. If the include/asm symlink is there, it will be removed.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

Python3 taken from the PATH causes build issues when pylibfdt bindings are
generated with Yocto SDK.

Python3 provided as a part of SDK is not compatible with host Python3,
therefore binding build breaks with following errors:

scripts/dtc/pylibfdt/libfdt_wrap.c:154:11: fatal error: Python.h: No such file or directory
  154 | # include <Python.h>
      |           ^~~~~~~~~~

Do not enforce the python3 from the PATH and make it conditionally-assigned
so it can be overridden from outside of build system. Keep the default
assignment to point to version that is taken from the PATH.

Similar fix has been introduced in b48bfc74ee ("tools: allow to override
python"), where conditional assignment is used for python executable to
address similar build errors.

Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Simon Glass <sjg@chromium.org>
Fixes: e91610da7c ("kconfig: re-sync with Linux 4.17-rc4")
Reviewed-by: Simon Glass <sjg@chromium.org>