[PATCH net-next v3 0/2] selftests: drv-net: Allow cross-compiling the hardware tests

[PATCH net-next v3 0/2] selftests: drv-net: Allow cross-compiling the hardware tests

[Maxime Chevallier (Netdev Foundation)]

Hi,

This is the third version for the ynl and drivers/net/hw
cross-compilation enablement series.

Changes come from Sashiko reviews, that detected some Makefile inclusion
ordering issues, a stray 'Q = @' in the ynl makefiles to have proper
verbosity support, and some commit log rewording.

Changes in V3:
 - Add Matthieu's review tags
 - Drop 'Q = @' line in patch 1, it's now handled properly through
   Makefile.include
 - Include Makefile.include before Makefile.arch
 - Reword the commit logs to explain the limitations

Changes in V2:
V2: https://lore.kernel.org/r/20260903155524.2241065-1-maxime.chevallier@bootlin.com
 - Update the topic for patch 1
 - Update the CC construction for patch 2

V1: https://lore.kernel.org/r/20260901164200.1124343-1-maxime.chevallier@bootlin.com

Maxime Chevallier (Netdev Foundation) (2):
  tools: ynl: Allow cross-compiling ynl and associated tools
  selftests: drv-net: Use cross-compilation environment for the io_uring
    check

 tools/net/ynl/Makefile                          | 1 +
 tools/net/ynl/generated/Makefile                | 3 ++-
 tools/net/ynl/lib/Makefile                      | 3 ++-
 tools/net/ynl/tests/Makefile                    | 2 +-
 tools/net/ynl/ynltool/Makefile                  | 6 ++----
 tools/testing/selftests/drivers/net/hw/Makefile | 5 +++++
 6 files changed, 13 insertions(+), 7 deletions(-)

-- 
2.55.0

[PATCH net-next v3 1/2] tools: ynl: Allow cross-compiling ynl and associated tools

[Maxime Chevallier (Netdev Foundation)]

The ynl tool and libraries may be built standalone or through the
drivers/net/hw selftest machinery. This may target a different arch, so
we need to take the CROSS_COMPILE variable into account for LLVM and
gcc.

Let's include the tools/scripts/Makefile.include that deals with the
CC/AR resolution.

Fixup the ynltool CFLAGS handling to use +=, so that we don't override
the ones set in Makefile.include.

Makefile.include also sets the Q variable for verbose mode, so we can
drop it from the ynltool Makefile. This will allow properly selection
the verbosity of ynltool builds with the V=1 make flag.

Reviewed-by: Matthieu Baerts (Netdev Foundation) <matttbe@kernel.org>
Signed-off-by: Maxime Chevallier (Netdev Foundation) <maxime.chevallier@bootlin.com>
---
 tools/net/ynl/Makefile           | 1 +
 tools/net/ynl/generated/Makefile | 3 ++-
 tools/net/ynl/lib/Makefile       | 3 ++-
 tools/net/ynl/tests/Makefile     | 2 +-
 tools/net/ynl/ynltool/Makefile   | 6 ++----
 5 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/tools/net/ynl/Makefile b/tools/net/ynl/Makefile
index 3cefe4ed96cb..838c465d65aa 100644
--- a/tools/net/ynl/Makefile
+++ b/tools/net/ynl/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
+include ../../scripts/Makefile.include
 include ../../scripts/Makefile.arch
 
 INSTALL	?= install
diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
index ea4128f612d6..5a186349b5a8 100644
--- a/tools/net/ynl/generated/Makefile
+++ b/tools/net/ynl/generated/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
-CC=gcc
+include ../../../scripts/Makefile.include
+
 CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
 	-I../lib/ -idirafter $(UAPI_PATH)
 ifeq ("$(DEBUG)","1")
diff --git a/tools/net/ynl/lib/Makefile b/tools/net/ynl/lib/Makefile
index 9b98c0599600..7b3eae89982f 100644
--- a/tools/net/ynl/lib/Makefile
+++ b/tools/net/ynl/lib/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
-CC=gcc
+include ../../../scripts/Makefile.include
+
 CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow
 ifeq ("$(DEBUG)","1")
   CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
diff --git a/tools/net/ynl/tests/Makefile b/tools/net/ynl/tests/Makefile
index 40827ca8e579..99ae7dcd6348 100644
--- a/tools/net/ynl/tests/Makefile
+++ b/tools/net/ynl/tests/Makefile
@@ -2,8 +2,8 @@
 # Makefile for YNL tests
 
 include ../Makefile.deps
+include ../../../scripts/Makefile.include
 
-CC=gcc
 CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
 	-I../lib/ -I../generated/ -I../../../testing/selftests/ \
 	-idirafter $(UAPI_PATH)
diff --git a/tools/net/ynl/ynltool/Makefile b/tools/net/ynl/ynltool/Makefile
index 48b0f32050f0..b8c67cdb4fdf 100644
--- a/tools/net/ynl/ynltool/Makefile
+++ b/tools/net/ynl/ynltool/Makefile
@@ -1,12 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 include ../Makefile.deps
+include ../../../scripts/Makefile.include
 
 INSTALL	?= install
 prefix  ?= /usr
 
-CC := gcc
-CFLAGS := -Wall -Wextra -Werror -O2
+CFLAGS += -Wall -Wextra -Werror -O2
 ifeq ("$(DEBUG)","1")
   CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
 endif
@@ -27,8 +27,6 @@ include $(wildcard *.d)
 
 all: $(YNLTOOL)
 
-Q = @
-
 $(YNLTOOL): ../libynl.a $(OBJS)
 	$(Q)echo -e "\tLINK $@"
 	$(Q)$(CC) $(CFLAGS) -o $@ $(OBJS) ../libynl.a -lm
-- 
2.55.0

Re: [PATCH net-next v3 1/2] tools: ynl: Allow cross-compiling ynl and associated tools

[netdev-bot+sashiko]

Thank you for your contribution! Sashiko AI review found 2 potential
issue(s) to consider:

Critical: 0 · High: 0 · Medium: 2 · Low: 0

- [Medium] tools/net/ynl/ynltool/Makefile now inherits the tools/ `O=` ->
  `OUTPUT` contract from tools/scripts/Makefile.include but only half-…
- [Medium] Removing the `CC=gcc` pin while letting Makefile.include
  select clang makes the GCC-only `-static-libasan` flag reach clang,…

--

tools: ynl: Allow cross-compiling ynl and associated tools

The four ynl Makefiles now include tools/scripts/Makefile.include so that
CC and AR honour CROSS_COMPILE and LLVM, the ynltool CFLAGS assignment is
switched from := to += and the local Q definition is dropped in favour of
the one from Makefile.include.

No Link: tags in the commit header.

Two questions below, one about O= handling in ynltool and one about
-static-libasan now that CC is no longer pinned to gcc.

> diff --git a/tools/net/ynl/Makefile b/tools/net/ynl/Makefile
> index 3cefe4ed96cb9..838c465d65aa8 100644
> --- a/tools/net/ynl/Makefile
> +++ b/tools/net/ynl/Makefile
> @@ -1,5 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> +include ../../scripts/Makefile.include
>  include ../../scripts/Makefile.arch
>  
>  INSTALL	?= install
> diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
> index ea4128f612d6c..5a186349b5a86 100644
> --- a/tools/net/ynl/generated/Makefile
> +++ b/tools/net/ynl/generated/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> -CC=gcc
> +include ../../../scripts/Makefile.include
> +
>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
>  	-I../lib/ -idirafter $(UAPI_PATH)
>  ifeq ("$(DEBUG)","1")
> diff --git a/tools/net/ynl/lib/Makefile b/tools/net/ynl/lib/Makefile
> index 9b98c05996000..7b3eae89982f8 100644
> --- a/tools/net/ynl/lib/Makefile
> +++ b/tools/net/ynl/lib/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> -CC=gcc
> +include ../../../scripts/Makefile.include
> +
>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow
>  ifeq ("$(DEBUG)","1")
>    CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
> diff --git a/tools/net/ynl/tests/Makefile b/tools/net/ynl/tests/Makefile
> index 40827ca8e579d..99ae7dcd63484 100644
> --- a/tools/net/ynl/tests/Makefile
> +++ b/tools/net/ynl/tests/Makefile
> @@ -2,8 +2,8 @@
>  # Makefile for YNL tests
>  
>  include ../Makefile.deps
> +include ../../../scripts/Makefile.include
>  
> -CC=gcc

[Severity: Medium]

With the CC=gcc pin removed here, does a "make LLVM=1 -C tools/net/ynl"
build still complete?  Makefile.include picks clang for LLVM builds:

  ifneq ($(LLVM),)
  ...
    $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))

and tests/Makefile turns the sanitizer flags on unless NDEBUG=1:

  ifneq ("$(NDEBUG)","1")
    CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
  endif

clang's driver does not accept -static-libasan.  Other selftests Makefiles
guard exactly this flag, for example
tools/testing/selftests/filesystems/openat2/Makefile:

  # gcc requires -static-libasan in order to ensure that Address Sanitizer's
  # library is the first one loaded. However, clang already statically links the
  # Address Sanitizer if -fsanitize is specified. Therefore, simply omit
  # -static-libasan for clang builds.
  ifeq ($(LLVM),)
      CFLAGS += -static-libasan
  endif

tests is listed in SUBDIRS of tools/net/ynl/Makefile and the default goal
is "all: $(SUBDIRS) libynl.a", so this is hit by a plain build with LLVM=1
(with or without CROSS_COMPILE, which is the configuration named in the
commit message).

The same unguarded flag sits on the DEBUG=1 paths of lib/Makefile,
generated/Makefile and ynltool/Makefile.  Should all four get the
ifeq ($(LLVM),) guard as part of this change?

>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
>  	-I../lib/ -I../generated/ -I../../../testing/selftests/ \
>  	-idirafter $(UAPI_PATH)
> diff --git a/tools/net/ynl/ynltool/Makefile b/tools/net/ynl/ynltool/Makefile
> index 48b0f32050f0e..b8c67cdb4fdf0 100644
> --- a/tools/net/ynl/ynltool/Makefile
> +++ b/tools/net/ynl/ynltool/Makefile
> @@ -1,12 +1,12 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  
>  include ../Makefile.deps
> +include ../../../scripts/Makefile.include

[Severity: Medium]

Does pulling Makefile.include in here break "make O=<dir>" for ynltool?
Makefile.include translates a command line O= into OUTPUT:

  ifneq ($(O),)
  ifeq ($(origin O), command line)
          $(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
	  ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd)
	  OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)

ynltool/Makefile already names its targets with that prefix:

  OBJS := $(patsubst %.c,$(OUTPUT)%.o,$(SRCS))

  YNLTOOL := $(OUTPUT)ynltool

but the only object rule carries no $(OUTPUT) and does not create the
directory:

  %.o: %.c ../libynl.a
	$(Q)echo -e "\tCC $@"
	$(Q)$(COMPILE.c) -MMD -c -o $@ $<

For a target such as /tmp/out/ynl.o and a target pattern containing no
slash, make strips the directory, matches the stem, and re-prepends the
directory to the derived prerequisite, so it looks for /tmp/out/ynl.c.
There is no vpath and nothing creates /tmp/out, so does
"make -C tools/net/ynl/ynltool O=/tmp/out" stop with "No rule to make
target '/tmp/out/<name>.o', needed by '/tmp/out/ynltool'"?

Command line variables propagate through MAKEFLAGS, and the top level
recipe runs the sub-makes with

  $(SUBDIRS):
	@if [ -f "$@/Makefile" ] ; then \
		$(MAKE) -C $@ ; \
	fi

so "make -C tools/net/ynl O=/tmp/out" reaches the same path through the
default goal.  Other tools/ Makefiles that honour this interface spell the
rule as $(OUTPUT)%.o: %.c - would that plus an mkdir be the fix here?

The install rule interpolates the prefixed name too:

  install: $(YNLTOOL)
	$(INSTALL) -m 0755 $(YNLTOOL) $(DESTDIR)$(bindir)/$(YNLTOOL)

With OUTPUT set, does the destination become
$(DESTDIR)/usr/bin//tmp/out/ynltool rather than $(DESTDIR)/usr/bin/ynltool?

Related: lib/Makefile, generated/Makefile and tests/Makefile now include
Makefile.include but ignore OUTPUT entirely, so an O= build would keep
writing their objects into the source tree while only ynltool tries to
honour it.  Was leaving the four sub-makefiles inconsistent about O=
intentional, or should O= be rejected until they all handle it?

>  
>  INSTALL	?= install
>  prefix  ?= /usr
>  
> -CC := gcc
> -CFLAGS := -Wall -Wextra -Werror -O2
> +CFLAGS += -Wall -Wextra -Werror -O2
>  ifeq ("$(DEBUG)","1")
>    CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
>  endif

[ ... ]

-- 
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260907161438.755125-1-maxime.chevallier%40bootlin.com

Re: [PATCH net-next v3 1/2] tools: ynl: Allow cross-compiling ynl and associated tools

[Bobby Eshleman]

On Mon, Sep 07, 2026 at 06:14:35PM +0200, Maxime Chevallier (Netdev Foundation) wrote:
> The ynl tool and libraries may be built standalone or through the
> drivers/net/hw selftest machinery. This may target a different arch, so
> we need to take the CROSS_COMPILE variable into account for LLVM and
> gcc.
> 
> Let's include the tools/scripts/Makefile.include that deals with the
> CC/AR resolution.
> 
> Fixup the ynltool CFLAGS handling to use +=, so that we don't override
> the ones set in Makefile.include.
> 
> Makefile.include also sets the Q variable for verbose mode, so we can
> drop it from the ynltool Makefile. This will allow properly selection
> the verbosity of ynltool builds with the V=1 make flag.
> 
> Reviewed-by: Matthieu Baerts (Netdev Foundation) <matttbe@kernel.org>
> Signed-off-by: Maxime Chevallier (Netdev Foundation) <maxime.chevallier@bootlin.com>

Hey Maxime,

It seems that this patch may break some invocations of make:

  # make -C tools/net/ynl/ynltool O=/tmp/o1
  make: Entering directory '/data/users/bobbyeshleman/linux-worktrees/review/tools/net/ynl/ynltool'
  make: *** No rule to make target '/tmp/o1/json_writer.o', needed by '/tmp/o1/ynltool'.  Stop.
  make: Leaving directory '/data/users/bobbyeshleman/linux-worktrees/review/tools/net/ynl/ynltool'

Best,
Bobby

> ---
>  tools/net/ynl/Makefile           | 1 +
>  tools/net/ynl/generated/Makefile | 3 ++-
>  tools/net/ynl/lib/Makefile       | 3 ++-
>  tools/net/ynl/tests/Makefile     | 2 +-
>  tools/net/ynl/ynltool/Makefile   | 6 ++----
>  5 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/net/ynl/Makefile b/tools/net/ynl/Makefile
> index 3cefe4ed96cb..838c465d65aa 100644
> --- a/tools/net/ynl/Makefile
> +++ b/tools/net/ynl/Makefile
> @@ -1,5 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> +include ../../scripts/Makefile.include
>  include ../../scripts/Makefile.arch
>  
>  INSTALL	?= install
> diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
> index ea4128f612d6..5a186349b5a8 100644
> --- a/tools/net/ynl/generated/Makefile
> +++ b/tools/net/ynl/generated/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> -CC=gcc
> +include ../../../scripts/Makefile.include
> +
>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
>  	-I../lib/ -idirafter $(UAPI_PATH)
>  ifeq ("$(DEBUG)","1")
> diff --git a/tools/net/ynl/lib/Makefile b/tools/net/ynl/lib/Makefile
> index 9b98c0599600..7b3eae89982f 100644
> --- a/tools/net/ynl/lib/Makefile
> +++ b/tools/net/ynl/lib/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> -CC=gcc
> +include ../../../scripts/Makefile.include
> +
>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow
>  ifeq ("$(DEBUG)","1")
>    CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
> diff --git a/tools/net/ynl/tests/Makefile b/tools/net/ynl/tests/Makefile
> index 40827ca8e579..99ae7dcd6348 100644
> --- a/tools/net/ynl/tests/Makefile
> +++ b/tools/net/ynl/tests/Makefile
> @@ -2,8 +2,8 @@
>  # Makefile for YNL tests
>  
>  include ../Makefile.deps
> +include ../../../scripts/Makefile.include
>  
> -CC=gcc
>  CFLAGS += -std=gnu11 -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow \
>  	-I../lib/ -I../generated/ -I../../../testing/selftests/ \
>  	-idirafter $(UAPI_PATH)
> diff --git a/tools/net/ynl/ynltool/Makefile b/tools/net/ynl/ynltool/Makefile
> index 48b0f32050f0..b8c67cdb4fdf 100644
> --- a/tools/net/ynl/ynltool/Makefile
> +++ b/tools/net/ynl/ynltool/Makefile
> @@ -1,12 +1,12 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  
>  include ../Makefile.deps
> +include ../../../scripts/Makefile.include
>  
>  INSTALL	?= install
>  prefix  ?= /usr
>  
> -CC := gcc
> -CFLAGS := -Wall -Wextra -Werror -O2
> +CFLAGS += -Wall -Wextra -Werror -O2
>  ifeq ("$(DEBUG)","1")
>    CFLAGS += -g -fsanitize=address -fsanitize=leak -static-libasan
>  endif
> @@ -27,8 +27,6 @@ include $(wildcard *.d)
>  
>  all: $(YNLTOOL)
>  
> -Q = @
> -
>  $(YNLTOOL): ../libynl.a $(OBJS)
>  	$(Q)echo -e "\tLINK $@"
>  	$(Q)$(CC) $(CFLAGS) -o $@ $(OBJS) ../libynl.a -lm
> -- 
> 2.55.0
> 

[PATCH net-next v3 2/2] selftests: drv-net: Use cross-compilation environment for the io_uring check

[Maxime Chevallier (Netdev Foundation)]

To test for the presence of zerocopy support in the available liburing,
a small check program is compiled.

The CC value used for the io_uring library check defaults to the host
compiler, which will incorrectly validate liburing based on the host's
sysroot and not the target's.

Normally the CC for cross-compile is set in lib.mk, but this also
requires the test list to be set when we include it, and this check
needs to run first.

Note that this doesn't cover the LLVM cross-compiling case though, as
with LLVM we may still detect based on the host liburing.

Suggested-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Matthieu Baerts (Netdev Foundation) <matttbe@kernel.org>
Signed-off-by: Maxime Chevallier (Netdev Foundation) <maxime.chevallier@bootlin.com>
---
 tools/testing/selftests/drivers/net/hw/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
index 6105be8e590f..f9458dc6c150 100644
--- a/tools/testing/selftests/drivers/net/hw/Makefile
+++ b/tools/testing/selftests/drivers/net/hw/Makefile
@@ -1,5 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0+ OR MIT
 
+# Set CC for the io_uring check
+ifeq ($(LLVM)$(CC),cc)
+CC := $(CROSS_COMPILE)gcc
+endif
+
 # Check if io_uring supports zero-copy receive
 HAS_IOURING_ZCRX := $(shell \
 	echo -e '#include <liburing.h>\n' \
-- 
2.55.0

Re: [PATCH net-next v3 2/2] selftests: drv-net: Use cross-compilation environment for the io_uring check

[netdev-bot+sashiko]

Thank you for your contribution! Sashiko AI review found 2 potential
issue(s) to consider:

Critical: 0 · High: 0 · Medium: 1 · Low: 1

- [Medium] Incomplete fix: the new guard `ifeq ($(LLVM)$(CC),cc)` in
  tools/testing/selftests/drivers/net/hw/Makefile only overrides CC when…
- [Low] Missing `Fixes:` tag.

--

selftests: drv-net: Use cross-compilation environment for the io_uring check

This sets CC to $(CROSS_COMPILE)gcc in the drivers/net/hw selftests
Makefile before the liburing feature probe runs, so that the probe uses the
target toolchain instead of the host compiler. The override is applied only
when make's CC is still the built-in default and LLVM is unset.

No Link: tag present in the commit header.

> diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
> index 6105be8e590f7..f9458dc6c1508 100644
> --- a/tools/testing/selftests/drivers/net/hw/Makefile
> +++ b/tools/testing/selftests/drivers/net/hw/Makefile
> @@ -1,5 +1,10 @@
>  # SPDX-License-Identifier: GPL-2.0+ OR MIT
>  
> +# Set CC for the io_uring check
> +ifeq ($(LLVM)$(CC),cc)
> +CC := $(CROSS_COMPILE)gcc
> +endif

[Severity: Medium]
Does this condition cover the case where CC comes from the environment
rather than from make's built-in default?

With something like:

    export CC=gcc-13
    make -C tools/testing/selftests/drivers/net/hw CROSS_COMPILE=aarch64-linux-gnu-

$(LLVM)$(CC) expands to gcc-13, so the override is skipped and the probe
below runs the host gcc-13. Later, lib.mk does:

    tools/testing/selftests/lib.mk:
    ifneq ($(LLVM),)
    CC := $(CLANG) $(CLANG_FLAGS) -fintegrated-as
    else
    CC := $(CROSS_COMPILE)gcc
    endif # LLVM

Since that is a := assignment in a makefile, it overrides the
environment-origin CC, so the compiler that actually links iou-zcrx is not
the one that was probed.

Would an origin test such as:

    ifeq ($(origin CC),default)

or mirroring lib.mk's own ifneq ($(LLVM),) ... else CC := $(CROSS_COMPILE)gcc
structure (as tools/testing/selftests/arm64/mte/Makefile does) make both
sides agree, and also close the LLVM case noted in the commit message?

[Severity: Low]
Should this carry a Fixes: tag?

git blame on the baseline attributes the whole probe block, including the
$(CC) -luring invocation and the COND_GEN_FILES += iou-zcrx gate, to:

    f81171fecd0c ("selftests: hw-net: auto-disable building the iouring C code")

Before that commit there was no CC-dependent probe in this Makefile. Adding
the tag would let backporters pick this up into trees that already carry
f81171fecd0c.

>  
>  # Check if io_uring supports zero-copy receive
>  HAS_IOURING_ZCRX := $(shell \
>  	echo -e '#include <liburing.h>\n' \

[Severity: Medium]
Related to the CC question above: the probe invokes only $(CC) -luring and
passes none of CFLAGS/CPPFLAGS/LDFLAGS/USERCFLAGS/USERLDFLAGS, while the
generic C rule in lib.mk does pass them when linking $(OUTPUT)/iou-zcrx.
Can a target liburing that is only reachable through user-supplied
-I/-L/sysroot flags stay invisible to this probe?

The two failure modes both come from the probe answering for a different
toolchain than the build:

    ifeq ($(HAS_IOURING_ZCRX),y)
    $(OUTPUT)/iou-zcrx: LDLIBS += -luring
    endif

Host-only liburing gives y and the cross link of iou-zcrx then fails on
-luring, taking the whole drivers/net/hw build with it. Target-only liburing
gives an empty value and the test is dropped with the warning "excluding
iouring tests, liburing not installed or too old".

[ ... ]

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Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260907161438.755125-1-maxime.chevallier%40bootlin.com

Re: [PATCH net-next v3 0/2] selftests: drv-net: Allow cross-compiling the hardware tests

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon,  7 Sep 2026 18:14:34 +0200 you wrote:
> Hi,
> 
> This is the third version for the ynl and drivers/net/hw
> cross-compilation enablement series.
> 
> Changes come from Sashiko reviews, that detected some Makefile inclusion
> ordering issues, a stray 'Q = @' in the ynl makefiles to have proper
> verbosity support, and some commit log rewording.
> 
> [...]

Here is the summary with links:
  - [net-next,v3,1/2] tools: ynl: Allow cross-compiling ynl and associated tools
    https://git.kernel.org/netdev/net-next/c/917f713b4ec4
  - [net-next,v3,2/2] selftests: drv-net: Use cross-compilation environment for the io_uring check
    https://git.kernel.org/netdev/net-next/c/0c5588740e22

You are awesome, thank you!
-- 
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Re: [PATCH net-next v3 0/2] selftests: drv-net: Allow cross-compiling the hardware tests

[Jakub Kicinski]

On Mon,  7 Sep 2026 18:14:34 +0200 Maxime Chevallier (Netdev
Foundation) wrote:
> Changes come from Sashiko reviews, that detected some Makefile inclusion
> ordering issues, a stray 'Q = @' in the ynl makefiles to have proper
> verbosity support, and some commit log rewording.

Looks good enough, if it works for you.
If we see a lot of follow ups and variance in the env people want 
to support we'll have to add some kind of a build test env on QEMU.