target specific KCONFIG fragments for kernel modules

[Tim Harvey]

On Fri, Feb 27, 2026 at 3:48 PM Tomasz Maciej Nowak <tmn505 at gmail.com> wrote:
>
> W dniu 27.02.2026 o 22:47, Tim Harvey pisze:
> > Greetings,
>
> Hi
>
> > I've been trying to figure out a way to create target specific KCONFIG
> > fragments in a KernelPackage and have not found anything that works.
> >
> > specifically I'm trying to enable HCIART_BCM for a specific target (as
> > my PR has not been accepted due to imposing a small increase in static
> > kernel size: https://github.com/openwrt/openwrt/pull/14517).
> >
> > Enabling the items in the target/subtarget config-default does not
> > work as the KCONFIG's in selected packages are applied after that so
> > I've been focusing on target specific changes in the KenrelPackage
> > definition.
> >
> > I have not been able to get something like the following to work:
> > define KernelPackage/hci-uart
> >   SUBMENU:=$(BLUETOOTH_MENU)
> >   TITLE:=Bluetooth HCI UART support
> >   DEPENDS:=+kmod-bluetooth
> > ifeq ($(CONFIG_TARGET_imx_cortexa53),y)
> >   KCONFIG:= \
> >         CONFIG_BT_HCIUART \
> >         CONFIG_BT_HCIUART_BCM=y \
> >         CONFIG_BT_HCIUART_SERDEV=y \
> >         CONFIG_SERIAL_DEV_CTRL_TTYPORT=y \
> >         CONFIG_SERIAL_DEV_BUS=y \
> >         CONFIG_BT_HCIUART_INTEL=n \
> >         CONFIG_BT_HCIUART_H4 \
> >         CONFIG_BT_HCIUART_NOKIA=n
> > else
> >   KCONFIG:= \
> >         CONFIG_BT_HCIUART \
> >         CONFIG_BT_HCIUART_BCM=n \
> >         CONFIG_BT_HCIUART_INTEL=n \
> >         CONFIG_BT_HCIUART_H4 \
> >         CONFIG_BT_HCIUART_NOKIA=n
> > endif
> >   FILES:= \
> >         $(LINUX_DIR)/drivers/bluetooth/hci_uart.ko \
> >         $(if $(CONFIG_BT_HCIUART_BCM),$(LINUX_DIR)/drivers/bluetooth/btbcm.ko)
> >   AUTOLOAD:=$(call AutoProbe,hci_uart)
> > endef
> >
> > Does anyone have any suggestions on how to accomplish this?
>
> Put CONFIG_SERIAL_DEV_CTRL_TTYPORT and CONFIG_SERIAL_DEV_BUS in kernel config
> of target You are targeting and use conditional in FILES like in my patch[1].
> That way any target including those tow symbols will have btbcm.ko available.
>
> 1. https://patchwork.ozlabs.org/project/openwrt/patch/20241029161046.110403-2-tmn505@terefe.re/
>

Hi Tomasz,

Thanks - I had not thought about moving certain deps into the target
kernel config.

Best Regards,

Tim



> > Best Regards,
> >
> > Tim
> Regards
>
> --
> TMN