en Copyright 2015 Java http://172.16.0.5:8080/history/linux-6.15/scripts/Makefile.userprogs#5f56cb03 kbuild: support 'userldlibs' syntaxThis syntax is useful to specify libraries linked to all userspaceprograms in the Makefile.Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> List of files: /linux-6.15/scripts/Makefile.userprogs Tue, 31 Oct 2023 18:11:57 +0000 Masahiro Yamada <masahiroy@kernel.org> http://172.16.0.5:8080/history/linux-6.15/scripts/Makefile.userprogs#7f3a59db kbuild: add infrastructure to build userspace programsKbuild supports the infrastructure to build host programs, but therewas no support to build userspace programs for the target architecture(i.e. the same architecture as the kernel).Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154),but it was not merged. One problem at that time was, there was no good wayto know whether $(CC) can link standalone programs. In fact, pre-builtkernel.org toolchains [1] are often used for building the kernel, but theydo not provide libc.Now, we can handle this cleanly because the compiler capability isevaluated at the Kconfig time. If $(CC) cannot link standalone programs,the relevant options are hidden by 'depends on CC_CAN_LINK'.The implementation just mimics scripts/Makefile.hostThe userspace programs are compiled with the same flags as the hostprograms. In addition, it uses -m32 or -m64 if it is found in$(KBUILD_CFLAGS).This new syntax has two usecases.- Sample programs Several userspace programs under samples/ include UAPI headers installed in usr/include. Most of them were previously built for the host architecture just to use the 'hostprogs' syntax. However, 'make headers' always works for the target architecture. This caused the arch mismatch in cross-compiling. To fix this distortion, sample code should be built for the target architecture.- Bpfilter net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper, and embeds it into the kernel. Currently, it overrides HOSTCC with CC to use the 'hostprogs' syntax. This hack should go away.[1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>Acked-by: Sam Ravnborg <sam@ravnborg.org> List of files: /linux-6.15/scripts/Makefile.userprogs Wed, 29 Apr 2020 03:45:14 +0000 Masahiro Yamada <masahiroy@kernel.org>