以 other.mk 中的iio 為例 對 KCONFIG下面的

define KernelPackage/iio-core
  SUBMENU:=$(OTHER_MENU)
  TITLE:=Industrial IO core
  KCONFIG:= \
    CONFIG_IIO \
    CONFIG_IIO_BUFFER=y \
    CONFIG_IIO_KFIFO_BUF \
    CONFIG_IIO_TRIGGER=y \
    CONFIG_IIO_TRIGGERED_BUFFER
  FILES:= \
    $(LINUX_DIR)/drivers/iio/industrialio.ko \
    $(if
 
 $(CONFIG_IIO_TRIGGERED_BUFFER),$(LINUX_DIR)/drivers/iio/industrialio-triggered-buffer.ko) \
    $(LINUX_DIR)/drivers/iio/kfifo_buf.ko
  AUTOLOAD:=$(call AutoLoad,55,industrialio kfifo_buf industrialio-triggered-buffer)
endef

define KernelPackage/iio-core/description
 The industrial I/O subsystem provides a unified framework for
 

 drivers for many different types of embedded sensors using a
 number of different physical interfaces (i2c, spi, etc)
endef

$(eval $(call KernelPackage,iio-core))

iio 跟目錄下Makefile部分內容

通過make menuconfig 選中 GONFIG_IIO後，編譯後，編譯的內容

GONFIG_IIO ：編譯了 industrialio-core.c inkern.c industrialio-event.c
CONFIG_IIO_BUFFER=y ： 編譯了 industrialio-buffer.c
CONFIG_IIO_TRIGGER=y ： 編譯了 industrialio-trigger.c
上述五個檔案共同編譯了元件： industrialio.ko

$(LINUX_DIR)/drivers/iio/kfifo_buf.ko // 這句話使得 kfifo_buf.ko 模組編譯，
                                    //但是CONFIG_IIO_KFIFO_BUF 沒有選中
                                    //說明，CONFIG_IIO_KFIFO_BUF=y對模組是否編譯無影響   

改變KCONFIG, 後再編譯

 KCONFIG:= \
    CONFIG_IIO \
    CONFIG_IIO_BUFFER=y \
    CONFIG_IIO_KFIFO_BUF \
    CONFIG_IIO_BUFFER_CB=y \
    CONFIG_IIO_TRIGGER \
    CONFIG_IIO_TRIGGERED_BUFFER=y \

並沒有出現 industrialio-triggered-buffer.ko 模組
同時 industrialio-buffer.c 也編譯了
與預期的不同，所需要看Kconfig檔案中的依賴關係

#
# Industrial I/O subsystem configuration
#

menuconfig IIO
    tristate "Industrial I/O support"
    select ANON_INODES
    help
      The industrial I/O subsystem provides a unified framework for
      drivers for many different types of embedded sensors using a
      number of different physical interfaces (i2c, spi, etc).

if IIO

config IIO_BUFFER
    bool "Enable buffer support within IIO"
    help
      Provide core support for various buffer based data
      acquisition methods.

if IIO_BUFFER

config IIO_BUFFER_CB
boolean "IIO callback buffer used for push in-kernel interfaces"
    help
      Should be selected by any drivers that do in-kernel push
      usage.  That is, those where the data is pushed to the consumer.

config IIO_KFIFO_BUF
    select IIO_TRIGGER
    tristate "Industrial I/O buffering based on kfifo"
    help
      A simple fifo based on kfifo.  Note that this currently provides
      no buffer events so it is up to userspace to work out how
      often to read from the buffer.

config IIO_TRIGGERED_BUFFER
    tristate
    select IIO_TRIGGER
    select IIO_KFIFO_BUF
    help
      Provides helper functions for setting up triggered buffers.

endif # IIO_BUFFER

config IIO_TRIGGER
    boolean "Enable triggered sampling support"
    help
      Provides IIO core support for triggers.  Currently these
      are used to initialize capture of samples to push into
      buffers.  The triggers are effectively a 'capture
      data now' interrupt.

config IIO_CONSUMERS_PER_TRIGGER
       int "Maximum number of consumers per trigger"
       depends on IIO_TRIGGER
       default "2"
       help
    This value controls the maximum number of consumers that a
    given trigger may handle. Default is 2.

更改KCONFIG，重新編譯：

    CONFIG_IIO \
    CONFIG_IIO_BUFFER \
    CONFIG_IIO_KFIFO_BUF \
    CONFIG_IIO_TRIGGER \
    CONFIG_IIO_TRIGGERED_BUFFER

可以看到，kfifo_buf.ko 模組沒有生成，是因為在Kconfig 檔案中看出 IIO_TRIGGER的依賴關係

config IIO_KFIFO_BUF
    select IIO_TRIGGER
//而 IIO_TRIGGER

但是僅僅選中 設定 CONFIG_IIO_TRIGGER=y 編譯也是通不過的，重新觀察發現 只有預先選中IIO_BUFFER, 才能選中_IIO_TRIGGER

if IIO_BUFFER

config IIO_BUFFER_CB
boolean “IIO callback buffer used for push in-kernel interfaces”
help
Should be selected by any drivers that do in-kernel push
usage. That is, those where the data is pushed to the consumer.

config IIO_KFIFO_BUF
select IIO_TRIGGER
tristate “Industrial I/O buffering based on kfifo”
help
A simple fifo based on kfifo. Note that this currently provides
no buffer events so it is up to userspace to work out how
often to read from the buffer.

config IIO_TRIGGERED_BUFFER
tristate
select IIO_TRIGGER
select IIO_KFIFO_BUF
help
Provides helper functions for setting up triggered buffers.

endif # IIO_BUFFER

更改KCONFIG，重新編譯：

    CONFIG_IIO \
    CONFIG_IIO_BUFFER=y \
    CONFIG_IIO_KFIFO_BUF \
    CONFIG_IIO_TRIGGER=y \
    CONFIG_IIO_TRIGGERED_BUFFER=y

並沒有出現 industrialio-triggered-buffer.ko 模組

CONFIG_IIO_KFIFO_BUF=y 設定後，再編譯還是沒有出現 industrialio-triggered-buffer.ko 模組，原因待查
當選中
CONFIG_IIO_KFIFO_BUF=y 後，
$(LINUX_DIR)/drivers/iio/kfifo_buf.ko 就不需要了