Re: [Buildroot] [PATCH] package/linux-tools: fix PCI endpoint tests build with recent kernels

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Florian,

Nice, nice, I stumbled across this issue yesterday, and I was
precisely looking at cooking a patch, but you beat me at it! Some
review/questions below.

On Thu, Oct 22, 2026 at 10:27:52AM -0700, Florian Fainelli wrote:
> Since Linux 6.14, the PCI endpoint tests have moved from tools/pci to
> tools/testing/selftests/pci_endpoint. The existing build commands still
> use the old location, causing the build to fail with newer kernels.
> 
> Detect the selftests directory and fall back to tools/pci for older
> kernels. Set OUTPUT and INSTALL_PATH to build and install the selftests
> under /usr/lib/kselftests/pci_endpoint, and pass the required libraries
> explicitly.
> 
> Add a threads dependency and update the help text to document the
> binary names and installation paths. Keep the minimum kernel version
> check for the legacy tools and report missing sources explicitly.
> 
> Fixes: 63e457639abb ("package/linux-tools: add support for pcitest tool")

Technically it doesn't fix this commit. At the time of 63e457639abb,
Linux 6.14 was not a thing, so 63e457639abb was correct. It's really
Linux 6.14 that broke stuff, so I don't think we can really point to a
particular Buildroot commit that is fixed by this change.

> diff --git a/package/linux-tools/Config.in b/package/linux-tools/Config.in
> index b9adc25ad51d..19d54cbbe707 100644
> --- a/package/linux-tools/Config.in
> +++ b/package/linux-tools/Config.in
> @@ -59,13 +59,18 @@ config BR2_PACKAGE_LINUX_TOOLS_MM
>  
>  config BR2_PACKAGE_LINUX_TOOLS_PCI
>  	bool "pci"
> +	depends on BR2_TOOLCHAIN_HAS_THREADS
>  	select BR2_PACKAGE_LINUX_TOOLS
>  	help
> -	  pcitest is a tool for testing capabilities related to a
> -	  PCI Endpoint (only works with specific Endpoints).
> +	  Build the PCI endpoint tests (only work with specific Endpoints).
> +	  Kernels before 6.14 provide pcitest in /usr/bin. Newer kernels
> +	  provide pci_endpoint_test in /usr/lib/kselftests/pci_endpoint.
>  
>  	  These tools are available only from kernel version 4.20.
>  
> +comment "pci needs a toolchain w/ threads"
> +	depends on !BR2_TOOLCHAIN_HAS_THREADS

Hm is this thread dependency new? With the Linux 6.14 change, or
unrelated?

>  comment "perf needs a toolchain w/ dynamic library, threads"
>  	depends on BR2_TOOLCHAIN_HAS_SYNC_4
>  	depends on BR2_STATIC_LIBS || !BR2_TOOLCHAIN_HAS_THREADS
> diff --git a/package/linux-tools/linux-tool-pci.mk.in b/package/linux-tools/linux-tool-pci.mk.in
> index 17246f5d7ed2..f9acf8f041d8 100644
> --- a/package/linux-tools/linux-tool-pci.mk.in
> +++ b/package/linux-tools/linux-tool-pci.mk.in
> @@ -6,22 +6,36 @@
>  
>  LINUX_TOOLS += pci
>  
> -PCI_MAKE_OPTS = $(LINUX_MAKE_FLAGS) LDFLAGS="$(TARGET_LDFLAGS)"
> +# Linux 6.14 moved the PCI endpoint tests into Kselftests.
> +PCI_SRCDIR = $(strip $(if $(wildcard $(LINUX_DIR)/tools/testing/selftests/pci_endpoint/Makefile),\
> +	$(LINUX_DIR)/tools/testing/selftests/pci_endpoint,$(LINUX_DIR)/tools/pci))

Aaaah nice. I hadn't thought of doing it like this.

> +PCI_MAKE_OPTS = $(LINUX_MAKE_FLAGS) \
> +	OUTPUT=$(PCI_SRCDIR)/ \
> +	LDFLAGS="$(TARGET_LDFLAGS)" \
> +	LDLIBS="-lrt -lpthread -lm"
>  
>  define PCI_BUILD_CMDS
> -	$(Q)if ! grep install $(LINUX_DIR)/tools/pci/Makefile >/dev/null 2>&1 ; then \
> +	$(Q)if test ! -f $(PCI_SRCDIR)/Makefile ; then \
> +		echo "Your kernel sources do not contain the PCI endpoint tests." ; \
> +		echo "Expected tools/pci or tools/testing/selftests/pci_endpoint." ; \
> +		exit 1 ; \
> +	fi
> +	$(Q)if test "$(PCI_SRCDIR)" = "$(LINUX_DIR)/tools/pci" && \
> +		! grep install $(PCI_SRCDIR)/Makefile >/dev/null 2>&1 ; then \

I'm wondering if we really need to grep for "install" in the
Makefile. Can't we just do:

	$(Q)if test ! -f $(PCI_SRCDIR)/Makefile; then
  		echo "Your kernel version is too old and does not have install section in the pci tools." ; \
  		echo "At least kernel 4.20 must be used." ; \
	fi

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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