Messages in this thread | | | Date | Wed, 18 Sep 2019 13:12:17 +0300 | From | Ivan Khoronzhuk <> | Subject | Re: [PATCH v3 bpf-next 07/14] samples: bpf: add makefile.target for separate CC target build |
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On Tue, Sep 17, 2019 at 04:19:40PM -0700, Andrii Nakryiko wrote: >On Mon, Sep 16, 2019 at 3:58 AM Ivan Khoronzhuk ><ivan.khoronzhuk@linaro.org> wrote: >> >> The makefile.target is added only and will be used in > >typo: Makefile > >> sample/bpf/Makefile later in order to switch cross-compiling on CC > >on -> to > >> from HOSTCC environment. >> >> The HOSTCC is supposed to build binaries and tools running on the host >> afterwards, in order to simplify build or so, like "fixdep" or else. >> In case of cross compiling "fixdep" is executed on host when the rest >> samples should run on target arch. In order to build binaries for >> target arch with CC and tools running on host with HOSTCC, lets add >> Makefile.target for simplicity, having definition and routines similar >> to ones, used in script/Makefile.host. This allows later add >> cross-compilation to samples/bpf with minimum changes. >> >> The tprog stands for target programs built with CC. > >Why tprog? Could we just use prog: hostprog vs prog. Prev. version was with prog, but Yonghong Song found it ambiguous. As prog can be bpf also. So, decision was made to follow logic: * target prog - non bpf progs * bpf prog = bpf prog, that can be later smth similar, providing build options for each bpf object separately.
Details here: https://lkml.org/lkml/2019/9/13/1037
> >> >> Makefile.target contains only stuff needed for samples/bpf, potentially >> can be reused later and now needed only for unblocking tricky >> samples/bpf cross compilation. >> >> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> >> --- >> samples/bpf/Makefile.target | 75 +++++++++++++++++++++++++++++++++++++ >> 1 file changed, 75 insertions(+) >> create mode 100644 samples/bpf/Makefile.target >> >> diff --git a/samples/bpf/Makefile.target b/samples/bpf/Makefile.target >> new file mode 100644 >> index 000000000000..fb6de63f7d2f >> --- /dev/null >> +++ b/samples/bpf/Makefile.target >> @@ -0,0 +1,75 @@ >> +# SPDX-License-Identifier: GPL-2.0 >> +# ========================================================================== >> +# Building binaries on the host system >> +# Binaries are not used during the compilation of the kernel, and intendent > >typo: intended > >> +# to be build for target board, target board can be host ofc. Added to build > >What's ofc, is it "of course"? yes, ofc )
> >> +# binaries to run not on host system. >> +# >> +# Sample syntax (see Documentation/kbuild/makefiles.rst for reference) >> +# tprogs-y := xsk_example >> +# Will compile xdpsock_example.c and create an executable named xsk_example > >You mix references to xsk_example and xdpsock_example, which is very >confusing. I'm guessing you meant to use xdpsock_example consistently. Oh, yes. Thanks.
> >> +# >> +# tprogs-y := xdpsock >> +# xdpsock-objs := xdpsock_1.o xdpsock_2.o >> +# Will compile xdpsock_1.c and xdpsock_2.c, and then link the executable >> +# xdpsock, based on xdpsock_1.o and xdpsock_2.o >> +# >> +# Inherited from scripts/Makefile.host > >"Inspired by" or "Derived from" would be probably more appropriate term :) I will replace with "Derived from", looks better.
> >> +# >> +__tprogs := $(sort $(tprogs-y)) >> + >> +# C code >> +# Executables compiled from a single .c file >> +tprog-csingle := $(foreach m,$(__tprogs), \ >> + $(if $($(m)-objs),,$(m))) >> + >> +# C executables linked based on several .o files >> +tprog-cmulti := $(foreach m,$(__tprogs),\ >> + $(if $($(m)-objs),$(m))) >> + >> +# Object (.o) files compiled from .c files >> +tprog-cobjs := $(sort $(foreach m,$(__tprogs),$($(m)-objs))) >> + >> +tprog-csingle := $(addprefix $(obj)/,$(tprog-csingle)) >> +tprog-cmulti := $(addprefix $(obj)/,$(tprog-cmulti)) >> +tprog-cobjs := $(addprefix $(obj)/,$(tprog-cobjs)) >> + >> +##### >> +# Handle options to gcc. Support building with separate output directory >> + >> +_tprogc_flags = $(TPROGS_CFLAGS) \ >> + $(TPROGCFLAGS_$(basetarget).o) >> + >> +# $(objtree)/$(obj) for including generated headers from checkin source files >> +ifeq ($(KBUILD_EXTMOD),) >> +ifdef building_out_of_srctree >> +_tprogc_flags += -I $(objtree)/$(obj) >> +endif >> +endif >> + >> +tprogc_flags = -Wp,-MD,$(depfile) $(_tprogc_flags) >> + >> +# Create executable from a single .c file >> +# tprog-csingle -> Executable >> +quiet_cmd_tprog-csingle = CC $@ >> + cmd_tprog-csingle = $(CC) $(tprogc_flags) $(TPROGS_LDFLAGS) -o $@ $< \ >> + $(TPROGS_LDLIBS) $(TPROGLDLIBS_$(@F)) >> +$(tprog-csingle): $(obj)/%: $(src)/%.c FORCE >> + $(call if_changed_dep,tprog-csingle) >> + >> +# Link an executable based on list of .o files, all plain c >> +# tprog-cmulti -> executable >> +quiet_cmd_tprog-cmulti = LD $@ >> + cmd_tprog-cmulti = $(CC) $(tprogc_flags) $(TPROGS_LDFLAGS) -o $@ \ >> + $(addprefix $(obj)/,$($(@F)-objs)) \ >> + $(TPROGS_LDLIBS) $(TPROGLDLIBS_$(@F)) >> +$(tprog-cmulti): $(tprog-cobjs) FORCE >> + $(call if_changed,tprog-cmulti) >> +$(call multi_depend, $(tprog-cmulti), , -objs) >> + >> +# Create .o file from a single .c file >> +# tprog-cobjs -> .o >> +quiet_cmd_tprog-cobjs = CC $@ >> + cmd_tprog-cobjs = $(CC) $(tprogc_flags) -c -o $@ $< >> +$(tprog-cobjs): $(obj)/%.o: $(src)/%.c FORCE >> + $(call if_changed_dep,tprog-cobjs) >> -- >> 2.17.1 >> > >tprogs is quite confusing, but overall looks good to me. I tend to leave it as tprogs, unless it's going to be progs and agreed with Yonghong.
It follows logic: - tprogs for bins - bpfprogs or bojs or bprogs (could be) for bpf obj
-- Regards, Ivan Khoronzhuk
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