Kbuild: don't build with clang -Oz for ARMv7-M
clang-8 fails to optimize out calls to __aeabi_ldivmod() for
64-bit division that are normally not emitted in any other
configuration, e.g.:
kernel/events/core.o: In function `perf_adjust_period':
mm/page-writeback.o: In function `balance_dirty_pages_ratelimited':
net/bridge/br_sysfs_br.o: In function `brforward_read':
drivers/usb/gadget/udc/atmel_usba_udc.o: In function `regs_dbg_open':
drivers/iio/imu/inv_mpu6050/inv_mpu_ring.o: In function `inv_mpu6050_read_fifo':
...: undefined reference to `__aeabi_ldivmod'
Add a special case for this so we don't offer that configuration
any more.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/init/Kconfig b/init/Kconfig
index e315fdf..098cdfb 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1131,6 +1131,7 @@
config CC_OPTIMIZE_FOR_SIZE
bool "Optimize for size"
imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
+ depends on !CC_IS_CLANG && ARM_SINGLE_ARMV7M
help
Enabling this option will pass "-Os" instead of "-O2" to
your compiler resulting in a smaller kernel.
