From: Arnd Bergmann <arnd@arndb.de>

When building with W=1, this variable is unused for configs with
CONFIG_CMA_SIZE_SEL_PERCENTAGE=y:

kernel/dma/contiguous.c:67:26: error: 'size_bytes' defined but not used [-Werror=unused-const-variable=]

Mark it as __maybe_unused to avoid the warning without adding more
ifdef checks to this file.

Fixes: c64be2bb1c6e ("drivers: add Contiguous Memory Allocator")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/dma/contiguous.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 055da410ac71..c53f4f633f7f 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -64,7 +64,7 @@ struct cma *dma_contiguous_default_area;
  * Users, who want to set the size of global CMA area for their system
  * should use cma= kernel parameter.
  */
-static const phys_addr_t size_bytes __initconst =
+static const phys_addr_t size_bytes __initconst __maybe_unused =
 	(phys_addr_t)CMA_SIZE_MBYTES * SZ_1M;
 static phys_addr_t  size_cmdline __initdata = -1;
 static phys_addr_t base_cmdline __initdata;
-- 
2.39.2

contiguous is misspelled in the subject.

Instead of the __maybe_unused annotation I'd just conver it to a
cpp #define.  I can take care of that if you want.