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linux/samples/Kconfig
Masahiro Yamada fca5e94921 samples: binderfs: really compile this sample and fix build issues 
Even after commit c624adc9cb ("samples: fix binderfs sample"), this
sample is never compiled.

'hostprogs' teaches Kbuild that this is a host program, but not enough
to order to compile it. You must add it to 'always-y' to really compile
it.

Since this sample has never been compiled in upstream, various issues
are left unnoticed.

[1] compilers without <linux/android/binderfs.h> are still widely used

<linux/android/binderfs.h> is only available since commit c13295ad21
("binderfs: rename header to binderfs.h"), i.e., Linux 5.0

If your compiler is based on UAPI headers older than Linux 5.0, you
will see the following error:

  samples/binderfs/binderfs_example.c:16:10: fatal error: linux/android/binderfs.h: No such file or directory
   #include <linux/android/binderfs.h>
            ^~~~~~~~~~~~~~~~~~~~~~~~~~
  compilation terminated.

You cannot rely on compilers having such a new header.

The common approach is to install UAPI headers of this kernel into
usr/include, and then add it to the header search path.

I added 'depends on HEADERS_INSTALL' in Kconfig, and '-I usr/include'
compiler flag in Makefile.

[2] compile the sample for target architecture

Because headers_install works for the target architecture, only the
native compiler was able to build sample code that requires
'-I usr/include'.

Commit 7f3a59db27 ("kbuild: add infrastructure to build userspace
programs") added the new syntax 'userprogs' to compile user-space
programs for the target architecture.

Use it, and then 'ifndef CROSS_COMPILE' will go away.

I added 'depends on CC_CAN_LINK' because $(CC) is not necessarily
capable of linking user-space programs.

[3] use subdir-y to descend into samples/binderfs

Since this directory does not contain any kernel-space code, it has no
point in generating built-in.a or modules.order.

Replace obj-$(CONFIG_...) with subdir-$(CONFIG_...).

[4] -Wunused-variable warning

If I compile this, I see the following warning.

  samples/binderfs/binderfs_example.c: In function 'main':
  samples/binderfs/binderfs_example.c:21:9: warning: unused variable 'len' [-Wunused-variable]
     21 |  size_t len;
        |         ^~~

I removed the unused 'len'.

[5] CONFIG_ANDROID_BINDERFS is not required

Since this is a user-space standalone program, it is independent of
the kernel configuration.

Remove 'depends on ANDROID_BINDERFS'.

Fixes: 9762dc1432 ("samples: add binderfs sample program")
Fixes: c624adc9cb ("samples: fix binderfs sample")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-06-11 20:14:41 +09:00

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# SPDX-License-Identifier: GPL-2.0-only
menuconfig SAMPLES
bool "Sample kernel code"
help
You can build and test sample kernel code here.
if SAMPLES
config SAMPLE_AUXDISPLAY
bool "auxdisplay sample"
depends on CC_CAN_LINK
config SAMPLE_TRACE_EVENTS
tristate "Build trace_events examples -- loadable modules only"
depends on EVENT_TRACING && m
help
This build trace event example modules.
config SAMPLE_TRACE_PRINTK
tristate "Build trace_printk module - tests various trace_printk formats"
depends on EVENT_TRACING && m
help
This builds a module that calls trace_printk() and can be used to
test various trace_printk() calls from a module.
config SAMPLE_FTRACE_DIRECT
tristate "Build register_ftrace_direct() example"
depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS && m
depends on X86_64 # has x86_64 inlined asm
help
This builds an ftrace direct function example
that hooks to wake_up_process and prints the parameters.
config SAMPLE_TRACE_ARRAY
tristate "Build sample module for kernel access to Ftrace instancess"
depends on EVENT_TRACING && m
help
This builds a module that demonstrates the use of various APIs to
access Ftrace instances from within the kernel.
config SAMPLE_KOBJECT
tristate "Build kobject examples"
help
This config option will allow you to build a number of
different kobject sample modules showing how to use kobjects,
ksets, and ktypes properly.
If in doubt, say "N" here.
config SAMPLE_KPROBES
tristate "Build kprobes examples -- loadable modules only"
depends on KPROBES && m
help
This build several kprobes example modules.
config SAMPLE_KRETPROBES
tristate "Build kretprobes example -- loadable modules only"
default m
depends on SAMPLE_KPROBES && KRETPROBES
config SAMPLE_HW_BREAKPOINT
tristate "Build kernel hardware breakpoint examples -- loadable module only"
depends on HAVE_HW_BREAKPOINT && m
help
This builds kernel hardware breakpoint example modules.
config SAMPLE_KFIFO
tristate "Build kfifo examples -- loadable modules only"
depends on m
help
This config option will allow you to build a number of
different kfifo sample modules showing how to use the
generic kfifo API.
If in doubt, say "N" here.
config SAMPLE_KDB
tristate "Build kdb command example -- loadable modules only"
depends on KGDB_KDB && m
help
Build an example of how to dynamically add the hello
command to the kdb shell.
config SAMPLE_QMI_CLIENT
tristate "Build qmi client sample -- loadable modules only"
depends on m
depends on ARCH_QCOM
depends on NET
select QCOM_QMI_HELPERS
help
Build an QMI client sample driver, which demonstrates how to
communicate with a remote QRTR service, using QMI encoded messages.
config SAMPLE_RPMSG_CLIENT
tristate "Build rpmsg client sample -- loadable modules only"
depends on RPMSG && m
help
Build an rpmsg client sample driver, which demonstrates how
to communicate with an AMP-configured remote processor over
the rpmsg bus.
config SAMPLE_LIVEPATCH
tristate "Build live patching samples -- loadable modules only"
depends on LIVEPATCH && m
help
Build sample live patch demonstrations.
config SAMPLE_CONFIGFS
tristate "Build configfs patching sample -- loadable modules only"
depends on CONFIGFS_FS && m
help
Builds a sample configfs interface.
config SAMPLE_CONNECTOR
tristate "Build connector sample -- loadable modules only"
depends on CONNECTOR && HEADERS_INSTALL && m
help
When enabled, this builds both a sample kernel module for
the connector interface and a user space tool to communicate
with it.
See also Documentation/driver-api/connector.rst
config SAMPLE_HIDRAW
bool "hidraw sample"
depends on CC_CAN_LINK && HEADERS_INSTALL
config SAMPLE_PIDFD
bool "pidfd sample"
depends on CC_CAN_LINK && HEADERS_INSTALL
config SAMPLE_SECCOMP
bool "Build seccomp sample code"
depends on SECCOMP_FILTER && CC_CAN_LINK && HEADERS_INSTALL
help
Build samples of seccomp filters using various methods of
BPF filter construction.
config SAMPLE_TIMER
bool "Timer sample"
depends on CC_CAN_LINK && HEADERS_INSTALL
config SAMPLE_UHID
bool "UHID sample"
depends on CC_CAN_LINK && HEADERS_INSTALL
help
Build UHID sample program.
config SAMPLE_VFIO_MDEV_MTTY
tristate "Build VFIO mtty example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
help
Build a virtual tty sample driver for use as a VFIO
mediated device
config SAMPLE_VFIO_MDEV_MDPY
tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
help
Build a virtual display sample driver for use as a VFIO
mediated device. It is a simple framebuffer and supports
the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
config SAMPLE_VFIO_MDEV_MDPY_FB
tristate "Build VFIO mdpy example guest fbdev driver -- loadable module only"
depends on FB && m
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
help
Guest fbdev driver for the virtual display sample driver.
config SAMPLE_VFIO_MDEV_MBOCHS
tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
depends on VFIO_MDEV_DEVICE && m
select DMA_SHARED_BUFFER
help
Build a virtual display sample driver for use as a VFIO
mediated device. It supports the region display interface
(VFIO_GFX_PLANE_TYPE_DMABUF).
Emulate enough of qemu stdvga to make bochs-drm.ko happy.
That is basically the vram memory bar and the bochs dispi
interface vbe registers in the mmio register bar.
Specifically it does *not* include any legacy vga stuff.
Device looks a lot like "qemu -device secondary-vga".
config SAMPLE_ANDROID_BINDERFS
bool "Build Android binderfs example"
depends on CC_CAN_LINK && HEADERS_INSTALL
help
Builds a sample program to illustrate the use of the Android binderfs
filesystem.
config SAMPLE_VFS
bool "Build example programs that use new VFS system calls"
depends on CC_CAN_LINK && HEADERS_INSTALL
help
Build example userspace programs that use new VFS system calls such
as mount API and statx(). Note that this is restricted to the x86
arch whilst it accesses system calls that aren't yet in all arches.
config SAMPLE_INTEL_MEI
bool "Build example program working with intel mei driver"
depends on INTEL_MEI
depends on CC_CAN_LINK && HEADERS_INSTALL
help
Build a sample program to work with mei device.
config SAMPLE_WATCHDOG
bool "watchdog sample"
depends on CC_CAN_LINK
endif # SAMPLES
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