chip: Remove -march, since -mcpu itself is sufficient

According to the GCC documentation:

-mcpu specifies the name of the target ARM processor. GCC uses this name
to derive the name of the target ARM architecture (as if specified by
-march) and the ARM processor type for which to tune for performance (as
if specified by -mtune).

https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html

This means that unless we're overriding some setting with -march or
-mtune, there's no need to specify them. In our case, we aren't
overriding the default for -mtune that -mcpu sets, so make things
simpler by only specifying -mcpu.

Additional details in
https://community.arm.com/arm-community-blogs/b/tools-software-ides-blog/posts/compiler-flags-across-architectures-march-mtune-and-mcpu

BRANCH=none
BUG=b:145677491
TEST=./util/compare_build.sh -b all -j 120
     => MATCH

Signed-off-by: Tom Hughes <tomhughes@chromium.org>
Change-Id: I1999ef25642ed9e32b2e8eeb76d4ba7a23dc2b8a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3699792
Reviewed-by: Andrea Grandi <agrandi@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/chip/npcx/build.mk b/chip/npcx/build.mk
index 1fe524763b..d7e61de4de 100644
--- a/chip/npcx/build.mk
+++ b/chip/npcx/build.mk
@@ -9,7 +9,7 @@
 # NPCX SoC has a Cortex-M4F ARM core
 CORE:=cortex-m
 # Allow the full Cortex-M4 instruction set
-CFLAGS_CPU+=-march=armv7e-m -mcpu=cortex-m4
+CFLAGS_CPU+=-mcpu=cortex-m4
 
 # Disable overlapping section warning that linker emits due to NPCX_RO_HEADER.
 LDFLAGS_EXTRA+=-Wl,--no-check-sections