[PATCH 0/5] clang: more warning and error fixes

[PATCH 0/5] clang: more warning and error fixes

[Ahmad Fatoum]

In preparation for making bare metal targets also compile with clang,
here are some more warning and error fixes for both assembler and compiler.

Ahmad Fatoum (5):
  kbuild: emit asm-offsets markers as .ascii strings
  scripts: imx9image: fix warnings reported by clang
  kbuild: disable -Wunused-but-set-variable after -Wall
  kbuild: disable -Winitializer-overrides for clang
  ARM64: cache: use WEAK() for v8_flush_l3_cache stub

 Makefile                   | 4 ----
 arch/arm/cpu/cache-armv8.S | 3 +--
 include/linux/kbuild.h     | 6 +++---
 scripts/Makefile.warn      | 8 ++++++++
 scripts/imx9image.c        | 9 ++-------
 5 files changed, 14 insertions(+), 16 deletions(-)

-- 
2.47.3

[PATCH 1/5] kbuild: emit asm-offsets markers as .ascii strings

[Ahmad Fatoum]

From: Ahmad Fatoum <a.fatoum@barebox.org>

The DEFINE()/BLANK()/COMMENT() macros emit their "->" markers as bare
lines, which clang's integrated assembler rejects:

  arch/arm/lib/asm-offsets.c:16:3: error: unexpected token at start of statement

Switch to the .ascii form from Linux commit cf0c3e68aa81 ("kbuild: fix
asm-offset generation to work with clang"). $(sed-offsets) already
handles both forms and the generated header is byte-identical.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 include/linux/kbuild.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/kbuild.h b/include/linux/kbuild.h
index de0f9bdb952f..6023904b5b67 100644
--- a/include/linux/kbuild.h
+++ b/include/linux/kbuild.h
@@ -4,14 +4,14 @@
 #define __LINUX_KBUILD_H
 
 #define DEFINE(sym, val) \
-	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+	asm volatile("\n.ascii \"->" #sym " %0 " #val "\"" : : "i" (val))
 
-#define BLANK() asm volatile("\n->" : : )
+#define BLANK() asm volatile("\n.ascii \"->\"" : : )
 
 #define OFFSET(sym, str, mem) \
 	DEFINE(sym, offsetof(struct str, mem))
 
 #define COMMENT(x) \
-	asm volatile("\n->#" x)
+	asm volatile("\n.ascii \"->#" x "\"")
 
 #endif
-- 
2.47.3

[PATCH 2/5] scripts: imx9image: fix warnings reported by clang

[Ahmad Fatoum]

From: Ahmad Fatoum <a.fatoum@barebox.org>

Host tools inherit -Werror with CONFIG_WERROR=y and clang fails on:

  scripts/imx9image.c:889:6: error: variable 'cont_img_count' set but not used [-Werror,-Wunused-but-set-variable]
  scripts/imx9image.c:1263:33: error: equality comparison with extraneous parentheses [-Werror,-Wparentheses-equality]

Drop the unused counter and the extra parentheses.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 scripts/imx9image.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/scripts/imx9image.c b/scripts/imx9image.c
index 61b7cc943f00..bd015a6ab7fc 100644
--- a/scripts/imx9image.c
+++ b/scripts/imx9image.c
@@ -886,7 +886,6 @@ static int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32
 	const char *platform;
 
 	int container = -1;
-	int cont_img_count = 0; /* indexes to arrange the container */
 
 	if (image_stack == NULL) {
 		fprintf(stderr, "Empty image stack ");
@@ -948,7 +947,6 @@ static int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32
 			img_sp->src = file_off;
 
 			file_off += ALIGN(sbuf.st_size, sector_size);
-			cont_img_count++;
 			break;
 
 		case DUMMY_V2X:
@@ -966,7 +964,6 @@ static int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32
 						images_hash);
 			img_sp->src = file_off;
 
-			cont_img_count++;
 			break;
 
 		case SECO:
@@ -986,7 +983,6 @@ static int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32
 			img_sp->src = file_off;
 
 			file_off += sbuf.st_size;
-			cont_img_count++;
 			break;
 
 		case NEW_CONTAINER:
@@ -995,7 +991,6 @@ static int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32
 					CONTAINER_ALIGNMENT,
 					CONTAINER_FLAGS_DEFAULT,
 					fuse_version);
-			cont_img_count = 0; /* reset img count when moving to new container */
 			scfw_flags = 0;
 			break;
 
@@ -1260,12 +1255,12 @@ static void print_image_array_fields(struct flash_header_v3 *container_hdrs, soc
 			if ((soc == ULP) || (soc == IMX9)) {
 				if (img_flags.core_id == CORE_ULP_UPOWER)
 					strcpy(img_name, "uPower FW");
-				else if ((img_flags.core_id == CORE_ULP_CA35))
+				else if (img_flags.core_id == CORE_ULP_CA35)
 					if (app_cntr)
 						strcpy(img_name, "A core Image");
 					else
 						strcpy(img_name, "Bootloader");
-				else if ((img_flags.core_id == CORE_ULP_CM33))
+				else if (img_flags.core_id == CORE_ULP_CM33)
 					strcpy(img_name, "M33");
 
 			} else {
-- 
2.47.3

[PATCH 3/5] kbuild: disable -Wunused-but-set-variable after -Wall

[Ahmad Fatoum]

From: Ahmad Fatoum <a.fatoum@barebox.org>

The top-level Makefile passes -Wno-unused-but-set-variable before
scripts/Makefile.warn adds -Wall. GCC keeps the warning disabled, but
clang processes options in order and re-enables it, failing dozens of
files with CONFIG_WERROR=y:

  drivers/video/edid.c:390:6: error: variable 'hfmin' set but not used [-Werror,-Wunused-but-set-variable]

Move the option after -Wall in scripts/Makefile.warn, where Linux'
scripts/Makefile.extrawarn has it.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 Makefile              | 4 ----
 scripts/Makefile.warn | 5 +++++
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index be81ac70403d..8762d2ae68b9 100644
--- a/Makefile
+++ b/Makefile
@@ -833,10 +833,6 @@ endif
 # Clear used registers at func exit (to reduce data lifetime and ROP gadgets).
 KBUILD_CFLAGS-$(CONFIG_ZERO_CALL_USED_REGS)	+= -fzero-call-used-regs=used-gpr
 
-# This warning generated too much noise in a regular build.
-# Use make W=1 to enable this warning (see scripts/Makefile.build)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-
 KBUILD_CFLAGS += $(call cc-disable-warning, trampolines)
 
 KBUILD_CFLAGS += $(call cc-option, -fno-delete-null-pointer-checks,)
diff --git a/scripts/Makefile.warn b/scripts/Makefile.warn
index a39c8223352a..393f7fd522c8 100644
--- a/scripts/Makefile.warn
+++ b/scripts/Makefile.warn
@@ -43,6 +43,11 @@ endif
 # disable pointer signed / unsigned warnings in gcc 4.0
 KBUILD_CFLAGS += -Wno-pointer-sign
 
+# Some diagnostics enabled by default are noisy. Unlike GCC, Clang re-enables
+# them when -Wall is passed later on the command line, so the -Wno... options
+# must come after -Wall
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+
 #
 # W=e and CONFIG_WERROR - error out on warnings
 #
-- 
2.47.3

[PATCH 4/5] kbuild: disable -Winitializer-overrides for clang

[Ahmad Fatoum]

From: Ahmad Fatoum <a.fatoum@barebox.org>

clang warns about the intentional [0 ... N] = default followed by
per-entry overrides, e.g. in arch/arm/cpu/interrupts_64.c:

  arch/arm/cpu/interrupts_64.c:28:26: error: initializer overrides prior initialization of this subobject [-Werror,-Winitializer-overrides]

Disable it for clang, as Linux does.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 scripts/Makefile.warn | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/Makefile.warn b/scripts/Makefile.warn
index 393f7fd522c8..237597d18af4 100644
--- a/scripts/Makefile.warn
+++ b/scripts/Makefile.warn
@@ -47,6 +47,9 @@ KBUILD_CFLAGS += -Wno-pointer-sign
 # them when -Wall is passed later on the command line, so the -Wno... options
 # must come after -Wall
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+ifdef CONFIG_CC_IS_CLANG
+KBUILD_CFLAGS += -Wno-initializer-overrides
+endif
 
 #
 # W=e and CONFIG_WERROR - error out on warnings
-- 
2.47.3

[PATCH 5/5] ARM64: cache: use WEAK() for v8_flush_l3_cache stub

[Ahmad Fatoum]

From: Ahmad Fatoum <a.fatoum@barebox.org>

clang's integrated assembler warns when a symbol is made weak after
being defined global:

  warning: v8_flush_l3_cache changed binding to STB_WEAK

Use WEAK() from linkage.h, which emits .weak before the label.

Assisted-by: Claude:fable-5
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 arch/arm/cpu/cache-armv8.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/cpu/cache-armv8.S b/arch/arm/cpu/cache-armv8.S
index e6f50886f924..b381da5e34d0 100644
--- a/arch/arm/cpu/cache-armv8.S
+++ b/arch/arm/cpu/cache-armv8.S
@@ -229,8 +229,7 @@ ENTRY(v8_invalidate_icache_all)
 ENDPROC(v8_invalidate_icache_all)
 
 .section .text.v8_flush_l3_cache
-ENTRY(v8_flush_l3_cache)
+WEAK(v8_flush_l3_cache)
 	mov	x0, #0			/* return status as success */
 	ret
 ENDPROC(v8_flush_l3_cache)
-	.weak	v8_flush_l3_cache
-- 
2.47.3

Re: [PATCH 0/5] clang: more warning and error fixes

[Sascha Hauer]

On Fri, 04 Sep 2026 09:59:12 +0200, Ahmad Fatoum wrote:
> In preparation for making bare metal targets also compile with clang,
> here are some more warning and error fixes for both assembler and compiler.
> 
> Ahmad Fatoum (5):
>   kbuild: emit asm-offsets markers as .ascii strings
>   scripts: imx9image: fix warnings reported by clang
>   kbuild: disable -Wunused-but-set-variable after -Wall
>   kbuild: disable -Winitializer-overrides for clang
>   ARM64: cache: use WEAK() for v8_flush_l3_cache stub
> 
> [...]

Applied, thanks!

[1/5] kbuild: emit asm-offsets markers as .ascii strings
      https://git.pengutronix.de/cgit/barebox/commit/?id=d0be5d7ff7d9 (link may not be stable)
[2/5] scripts: imx9image: fix warnings reported by clang
      https://git.pengutronix.de/cgit/barebox/commit/?id=0ed92a5f4ca1 (link may not be stable)
[3/5] kbuild: disable -Wunused-but-set-variable after -Wall
      https://git.pengutronix.de/cgit/barebox/commit/?id=52d6a7a60bae (link may not be stable)
[4/5] kbuild: disable -Winitializer-overrides for clang
      https://git.pengutronix.de/cgit/barebox/commit/?id=9c787cdf53df (link may not be stable)
[5/5] ARM64: cache: use WEAK() for v8_flush_l3_cache stub
      https://git.pengutronix.de/cgit/barebox/commit/?id=69b498bb79a5 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>