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author | Paul Burton <paul.burton@mips.com> | 2019-01-11 19:06:44 +0000 |
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committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-01-14 10:37:09 +0900 |
commit | 16fd20aa98080c2fa666dc384036ec08c80af710 (patch) | |
tree | d8265dede17c209f3328939ead6402383b345a84 /kernel/sys.c | |
parent | 2648ca1859bb48cacdbbaf60bbc0bfef74f13330 (diff) | |
download | linux-16fd20aa98080c2fa666dc384036ec08c80af710.tar.bz2 |
kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7
When building using GCC 4.7 or older, -ffunction-sections & the -pg flag
used by ftrace are incompatible. This causes warnings or build failures
(where -Werror applies) such as the following:
arch/mips/generic/init.c:
error: -ffunction-sections disabled; it makes profiling impossible
This used to be taken into account by the ordering of calls to cc-option
from within the top-level Makefile, which was introduced by commit
90ad4052e85c ("kbuild: avoid conflict between -ffunction-sections and
-pg on gcc-4.7"). Unfortunately this was broken when the
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION cc-option check was moved to
Kconfig in commit e85d1d65cd8a ("kbuild: test dead code/data elimination
support in Kconfig"), because the flags used by this check no longer
include -pg.
Fix this by not allowing CONFIG_LD_DEAD_CODE_DATA_ELIMINATION to be
enabled at the same time as ftrace/CONFIG_FUNCTION_TRACER when building
using GCC 4.7 or older.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: e85d1d65cd8a ("kbuild: test dead code/data elimination support in Kconfig")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'kernel/sys.c')
0 files changed, 0 insertions, 0 deletions