In tree libraries which link against other in tree libraries in a way which is opaque to their callers need special handling, specifically correct use of -Wl,-rpath-link for the recusively used libraries.
Currently this is rather simple, but up coming changes are going to introduce transitive dependencies more than 1 step deep. Introduce a SHDEPS idiom to contain all the recursive deps for a library and include those in both LDLIBS (for linking) and SHLIB (for recursive uses). Try and document the whole thing. Signed-off-by: Ian Campbell <ian.campb...@citrix.com> Acked-by: Ian Jackson <ian.jack...@eu.citrix.com> Acked-by: Wei Liu <wei.l...@citrix.com> --- v5: Handled rebase over removal of stray L in rpath-link. v4: Unmanged description of libbaz. --- tools/Rules.mk | 74 ++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 62 insertions(+), 12 deletions(-) diff --git a/tools/Rules.mk b/tools/Rules.mk index ffa5fd3..37b0aaf 100644 --- a/tools/Rules.mk +++ b/tools/Rules.mk @@ -34,25 +34,72 @@ INSTALL_SHLIB = : install-shlib-unsupported-fail SYMLINK_SHLIB = : symlink-shlib-unsupported-fail endif +# Compiling and linking against in tree libraries. +# +# In order to compile and link against an in-tree library various +# cpp/compiler/linker options are required. +# +# For example consider a library "libfoo" which itself uses two other +# libraries: +# libbar - whose use is entirely internal to libfoo and not exposed +# to users of libfoo at all. +# libbaz - whose use is entirely internal to libfoo but libfoo's +# public headers include one or more of libbaz's +# public headers. Users of libfoo are therefore transitively +# using libbaz's header but not linking against libbaz. +# +# SHDEPS_libfoo: Flags for linking recursive dependencies of +# libfoo. Must contain SHLIB for every library which +# libfoo links against. So must contain both +# $(SHLIB_libbar) and $(SHLIB_libbaz). +# +# SHLIB_libfoo: Flags for recursively linking against libfoo. Must +# contains SHDEPS_libfoo and: +# -Wl,-rpath-link=<directory containing libfoo.so> +# +# CFLAGS_libfoo: Flags for compiling against libfoo. Must add the +# directories containing libfoo's headers to the +# include path. Must recursively include +# $(CFLAGS_libbaz), to satisfy the transitive inclusion +# of the headers but not $(CFLAGS_libbar) since none of +# libbar's headers are required to build against +# libfoo. +# +# LDLIBS_libfoo: Flags for linking against libfoo. Must contain +# $(SHDEPS_libfoo) and the path to libfoo.so +# +# Consumers of libfoo should include $(CFLAGS_libfoo) and +# $(LDLIBS_libfoo) in their appropriate directories. They should not +# include any CFLAGS or LDLIBS relating to libbar or libbaz unless +# they use those libraries directly (not via libfoo) too. +# +# Consumers of libfoo should not directly use $(SHDEPS_libfoo) or +# $(SHLIB_libfoo) + CFLAGS_libxenctrl = -I$(XEN_LIBXC)/include $(CFLAGS_xeninclude) +SHDEPS_libxenctrl = LDLIBS_libxenctrl = $(XEN_LIBXC)/libxenctrl$(libextension) SHLIB_libxenctrl = -Wl,-rpath-link=$(XEN_LIBXC) CFLAGS_libxenguest = -I$(XEN_LIBXC)/include $(CFLAGS_xeninclude) -LDLIBS_libxenguest = $(XEN_LIBXC)/libxenguest$(libextension) -SHLIB_libxenguest = -Wl,-rpath-link=$(XEN_LIBXC) +SHDEPS_libxenguest = +LDLIBS_libxenguest = $(SHDEPS_libxenguest) $(XEN_LIBXC)/libxenguest$(libextension) +SHLIB_libxenguest = $(SHDEPS_libxenguest) -Wl,-rpath-link=$(XEN_LIBXC) CFLAGS_libxenstore = -I$(XEN_XENSTORE)/include $(CFLAGS_xeninclude) -LDLIBS_libxenstore = $(XEN_XENSTORE)/libxenstore$(libextension) -SHLIB_libxenstore = -Wl,-rpath-link=$(XEN_XENSTORE) +SHDEPS_libxenstore = +LDLIBS_libxenstore = $(SHDEPS_libxenguest) $(XEN_XENSTORE)/libxenstore$(libextension) +SHLIB_libxenstore = $(SHDEPS_libxenguest) -Wl,-rpath-link=$(XEN_XENSTORE) CFLAGS_libxenstat = -I$(XEN_LIBXENSTAT) -LDLIBS_libxenstat = $(SHLIB_libxenctrl) $(SHLIB_libxenstore) $(XEN_LIBXENSTAT)/libxenstat$(libextension) -SHLIB_libxenstat = -Wl,-rpath-link=$(XEN_LIBXENSTAT) +SHDEPS_libxenstat = $(SHLIB_libxenctrl) $(SHLIB_libxenstore) +LDLIBS_libxenstat = $(SHDEPS_libxenstat) $(XEN_LIBXENSTAT)/libxenstat$(libextension) +SHLIB_libxenstat = $(SHDEPS_libxenstat) -Wl,-rpath-link=$(XEN_LIBXENSTAT) CFLAGS_libxenvchan = -I$(XEN_LIBVCHAN) -LDLIBS_libxenvchan = $(SHLIB_libxenctrl) $(SHLIB_libxenstore) $(XEN_LIBVCHAN)/libxenvchan$(libextension) -SHLIB_libxenvchan = -Wl,-rpath-link=$(XEN_LIBVCHAN) +SHDEPS_libxenvchan = $(SHLIB_libxenctrl) $(SHLIB_libxenstore) +LDLIBS_libxenvchan = $(SHDEPS_libxenvchan) $(XEN_LIBVCHAN)/libxenvchan$(libextension) +SHLIB_libxenvchan = $(SHDEPS_libxenvchan) -Wl,-rpath-link=$(XEN_LIBVCHAN) ifeq ($(debug),y) # Disable optimizations and enable debugging information for macros @@ -65,17 +112,20 @@ LIBXL_BLKTAP ?= $(CONFIG_BLKTAP2) ifeq ($(LIBXL_BLKTAP),y) CFLAGS_libblktapctl = -I$(XEN_BLKTAP2)/control -I$(XEN_BLKTAP2)/include $(CFLAGS_xeninclude) -LDLIBS_libblktapctl = $(XEN_BLKTAP2)/control/libblktapctl$(libextension) -SHLIB_libblktapctl = -Wl,-rpath-link=$(XEN_BLKTAP2)/control +SHDEPS_libblktapctl = +LDLIBS_libblktapctl = $(SHDEPS_libblktapctl) $(XEN_BLKTAP2)/control/libblktapctl$(libextension) +SHLIB_libblktapctl = $(SHDEPS_libblktapctl) -Wl,-rpath-link=$(XEN_BLKTAP2)/control else CFLAGS_libblktapctl = +SHDEPS_libblktapctl = LDLIBS_libblktapctl = SHLIB_libblktapctl = endif CFLAGS_libxenlight = -I$(XEN_XENLIGHT) $(CFLAGS_libxenctrl) $(CFLAGS_xeninclude) -LDLIBS_libxenlight = $(XEN_XENLIGHT)/libxenlight$(libextension) $(SHLIB_libxenctrl) $(SHLIB_libxenstore) $(SHLIB_libblktapctl) -SHLIB_libxenlight = -Wl,-rpath-link=$(XEN_XENLIGHT) +SHDEPS_libxenlight = $(SHLIB_libxenctrl) $(SHLIB_libxenstore) $(SHLIB_libblktapctl) +LDLIBS_libxenlight = $(SHDEPS_libxenlight) $(XEN_XENLIGHT)/libxenlight$(libextension) +SHLIB_libxenlight = $(SHDEPS_libxenlight) -Wl,-rpath-link=$(XEN_XENLIGHT) CFLAGS += -D__XEN_TOOLS__ -- 2.1.4 _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
