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2020-08-09kbuild: introduce hostprogs-always-y and userprogs-always-yMasahiro Yamada1-2/+1
To build host programs, you need to add the program names to 'hostprogs' to use the necessary build rule, but it is not enough to build them because there is no dependency. There are two types of host programs: built as the prerequisite of another (e.g. gen_crc32table in lib/Makefile), or always built when Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile). The latter is typical in Makefiles under scripts/, which contains host programs globally used during the kernel build. To build them, you need to add them to both 'hostprogs' and 'always-y'. This commit adds hostprogs-always-y as a shorthand. The same applies to user programs. net/bpfilter/Makefile builds bpfilter_umh on demand, hence always-y is unneeded. In contrast, programs under samples/ are added to both 'userprogs' and 'always-y' so they are always built when Kbuild visits the Makefiles. userprogs-always-y works as a shorthand. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2020-06-13binderfs: add gitignore for generated sample programLinus Torvalds1-0/+1
Let's keep "git status" happy and quiet. Fixes: 9762dc1432e1 ("samples: add binderfs sample program Fixes: fca5e94921d5 ("samples: binderfs: really compile this sample and fix build issues") Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-11samples: binderfs: really compile this sample and fix build issuesMasahiro Yamada2-6/+4
Even after commit c624adc9cb6e ("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 c13295ad219d ("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 7f3a59db274c ("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: 9762dc1432e1 ("samples: add binderfs sample program") Fixes: c624adc9cb6e ("samples: fix binderfs sample") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
2020-05-05samples: fix binderfs sampleArnd Bergmann1-1/+5
A routine check for misspelled Kconfig symbols showed on instance from last year, the correct symbol name is CONFIG_ANDROID_BINDERFS, not CONFIG_CONFIG_ANDROID_BINDERFS, so the extra prefix must be removed in the Kconfig file to allow enabling the sample. As the actual sample fails to build as a kernel module, change the Makefile enough to get to build as a hostprog instead. Fixes: 9762dc1432e1 ("samples: add binderfs sample program") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200428212555.2806258-1-arnd@arndb.de Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner1-0/+1
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-15samples: add binderfs sample programChristian Brauner2-0/+84
This adds a simple sample program mounting binderfs and adding, then removing a binder device. Hopefully, it will be helpful to users who want to know how binderfs is supposed to be used. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>