linux-kernel - Re: [PATCH] PCI: endpoint: pci-epf-test: select configfs

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Message-ID: <aYxGR-x3lGt7H1dp@ryzen>
Date: Wed, 11 Feb 2026 10:05:11 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Manivannan Sadhasivam <mani@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Damien Le Moal <dlemoal@...nel.org>, Frank Li <Frank.Li@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: endpoint: pci-epf-test: select configfs

On Wed, Feb 11, 2026 at 08:07:40AM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> Like some of the other endpoint modules, this one now also
> uses configfs, but is missing an indication in Kconfig:
> 
> arm-linux-gnueabi-ld: drivers/pci/endpoint/functions/pci-epf-test.o: in function `pci_epf_test_add_cfs':
> pci-epf-test.c:(.text.pci_epf_test_add_cfs+0x2c): undefined reference to `config_group_init_type_name'
> 
> Select the symbol as needed.
> 
> Fixes: ffcc4850a161 ("PCI: endpoint: pci-epf-test: Allow overriding default BAR sizes")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/pci/endpoint/functions/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/endpoint/functions/Kconfig b/drivers/pci/endpoint/functions/Kconfig
> index 0c9cea0698d7..bb5a23994288 100644
> --- a/drivers/pci/endpoint/functions/Kconfig
> +++ b/drivers/pci/endpoint/functions/Kconfig
> @@ -6,6 +6,7 @@
>  config PCI_EPF_TEST
>  	tristate "PCI Endpoint Test driver"
>  	depends on PCI_ENDPOINT
> +	select CONFIGFS_FS
>  	select CRC32
>  	help
>  	   Enable this configuration option to enable the test driver
> -- 
> 2.39.5
> 

Patch is fine with me:
Reviewed-by: Niklas Cassel <cassel@...nel.org>


However, I remember that you Arnd was one of the main reasons why Kishon
decided to use configfs to configure a PCI endpoint controller and to
bind a PCI endpoint function driver with a PCI endpoint controller.

I don't know of any other way than configfs to bind a PCI endpoint function
driver with a PCI endpoint controller.

To me, it seems a bit silly to be able to build PCI_ENDPOINT without
configfs. What should a user do with a library that they cannot bind to
a PCI endpoint controller?

Why shouldn't we just do something like:

diff --git a/drivers/pci/endpoint/Kconfig b/drivers/pci/endpoint/Kconfig
index 8dad291be8b8..d6f898094509 100644
--- a/drivers/pci/endpoint/Kconfig
+++ b/drivers/pci/endpoint/Kconfig
@@ -8,6 +8,7 @@ menu "PCI Endpoint"
 config PCI_ENDPOINT
 	bool "PCI Endpoint Support"
 	depends on HAVE_PCI
+	select PCI_ENDPOINT_CONFIGFS
 	help
 	   Enable this configuration option to support configurable PCI
 	   endpoint. This should be enabled if the platform has a PCI
diff --git a/drivers/pci/endpoint/functions/Kconfig b/drivers/pci/endpoint/functions/Kconfig
index 0c9cea0698d7..d7a4bea7d7b8 100644
--- a/drivers/pci/endpoint/functions/Kconfig
+++ b/drivers/pci/endpoint/functions/Kconfig
@@ -16,7 +16,6 @@ config PCI_EPF_TEST
 config PCI_EPF_NTB
 	tristate "PCI Endpoint NTB driver"
 	depends on PCI_ENDPOINT
-	select CONFIGFS_FS
 	help
 	  Select this configuration option to enable the Non-Transparent
 	  Bridge (NTB) driver for PCI Endpoint. NTB driver implements NTB
@@ -30,7 +29,6 @@ config PCI_EPF_VNTB
 	tristate "PCI Endpoint Virtual NTB driver"
 	depends on PCI_ENDPOINT
 	depends on NTB
-	select CONFIGFS_FS
 	help
 	  Select this configuration option to enable the Non-Transparent
 	  Bridge (NTB) driver for PCIe Endpoint. NTB driver implements NTB