genode/repos/base/mk/dep_lib.mk
Norman Feske 4da52517c1 Simpify startup of dynamically linked binaries
This patch removes the component_entry_point library, which used to
proved a hook for the libc to intercept the call of the
'Component::construct' function. The mechansim has several shortcomings
(see the discussion in the associated issue) and was complex. So we
eventually discarded the approach in favor of the explicit handling of
the startup.

A regular Genode component provides a 'Component::construct' function,
which is determined by the dynamic linker via a symbol lookup.
For the time being, the dynamic linker falls back to looking up a 'main'
function if no 'Component::construct' function could be found.

The libc provides an implementation of 'Component::construct', which
sets up the libc's task handling and finally call the function
'Libc::Component::construct' from the context of the appllication task.
This function is expected to be provided by the libc-using application.
Consequently, Genode components that use the libc have to implement the
'Libc::Component::construct' function.

The new 'posix' library provides an implementation of
'Libc::Component::construct' that calls a main function. Hence, POSIX
programs that merely use the POSIX API merely have to add 'posix' to the
'LIBS' declaration in their 'target.mk' file. Their execution starts at
'main'.

Issue #2199
2017-01-13 13:06:52 +01:00

160 lines
5.0 KiB
Makefile

#
# This file determines dependencies of a library from other libraries
#
# The following variables must be defined by the caller:
#
# VERBOSE - controls the make verboseness
# VERBOSE_DIR - verboseness of directory change messages
# VERBOSE_MK - verboseness of make calls
# REPOSITORIES - source code repositories to use
# BASE_DIR - base directory of build system repository
# TARGET_DIR - target build directory
# BUILD_BASE_DIR - build directory with build config
# LIB_CACHE_DIR - destination directory for object files
# LIB_PROGRESS_LOG - library build log file
# BUILD_LIBS - list of libraries to build (without .lib.a or .lib.so suffix)
# INSTALL_DIR - destination directory for installing shared libraries
#
ACCUMULATE_MISSING_PORTS = 1
#
# Include common utility functions
#
include $(BASE_DIR)/mk/util.inc
#
# Generate dependencies only for those libs that are
# not already contained in the library build log
#
include $(LIB_PROGRESS_LOG)
ifneq ($(filter $(LIB),$(LIBS_READY)),)
already_visited:
@true
else
all: append_lib_to_progress_log
endif
append_lib_to_progress_log:
@echo "LIBS_READY += $(LIB)" >> $(LIB_PROGRESS_LOG)
LIB_MK_DIRS = $(foreach REP,$(REPOSITORIES),$(addprefix $(REP)/lib/mk/spec/,$(SPECS)) $(REP)/lib/mk)
#
# Of all possible file locations, use the (first) one that actually exist.
#
LIB_MK = $(firstword $(wildcard $(addsuffix /$(LIB).mk,$(LIB_MK_DIRS))))
#
# Sanity check to detect missing library description file
#
ifeq ($(LIB_MK),)
all: warn_missing_lib_mk
else
all: check_unsatisfied_requirements
endif
warn_missing_lib_mk: generate_lib_rule_for_defect_library
@$(ECHO) "Library-description file $(DARK_COL)$(LIB).mk$(DEFAULT_COL) is missing"
#
# Determine the repository base directory from the absolute pathname
# of the choosen libname.mk file. We need to specify the override
# command because REP_DIR was first set by prg.mk when building a
# program target. The repository of a library could be a different
# one.
#
# Finally, we strip the trailing slash from the path. The slash was
# used to match the whole directory in 'findstring'.
#
override REP_DIR := $(firstword $(foreach REP,$(REPOSITORIES),$(findstring $(REP)/,$(LIB_MK))))
override REP_DIR := $(REP_DIR:/=)
include $(BASE_DIR)/mk/base-libs.mk
include $(LIB_MK)
ifdef SHARED_LIB
#
# For shared libraries, we have to make sure to build ldso support before
# building a shared library.
#
LIBS += ldso-startup
ifneq ($(LIB),$(DYNAMIC_LINKER))
LIBS += $(DYNAMIC_LINKER)
endif
#
# Ensure that startup_dyn is build for the dynamic programs that depend on a
# shared library. They add it to their dependencies as replacement for the
# static-case startup as soon as they recognize that they are dynamic.
# The current library in contrast filters-out startup_dyn from its
# dependencies before they get merged.
#
DEP_VAR_NAME := DEP_$(LIB).lib.so
else
DEP_VAR_NAME := DEP_$(LIB).lib
endif
#
# Add platform preparation dependency
#
# We make each leaf library depend on a library called 'platform'. This way,
# the 'platform' library becomes a prerequisite of all other libraries. The
# 'platform' library is supposed to take precautions for setting up
# platform-specific build environments, e.g., preparing kernel API headers.
#
ifeq ($(LIBS),)
ifneq ($(LIB),platform)
LIBS += platform
endif
endif
#
# Check if the requirements of the target are satisfied
#
UNSATISFIED_REQUIREMENTS = $(filter-out $(SPECS),$(REQUIRES))
ifneq ($(UNSATISFIED_REQUIREMENTS),)
check_unsatisfied_requirements: warn_unsatisfied_requirements
else
check_unsatisfied_requirements: generate_lib_rule
endif
warn_unsatisfied_requirements: generate_lib_rule_for_defect_library
@$(ECHO) "Skip library $(LIB) because it requires $(DARK_COL)$(UNSATISFIED_REQUIREMENTS)$(DEFAULT_COL)"
generate_lib_rule_for_defect_library:
@echo "INVALID_DEPS += $(LIB)" >> $(LIB_DEP_FILE)
@echo "" >> $(LIB_DEP_FILE)
LIBS_TO_VISIT = $(filter-out $(LIBS_READY),$(LIBS))
generate_lib_rule:
ifneq ($(LIBS),)
@(echo "$(DEP_VAR_NAME) = $(foreach l,$(LIBS),$l.lib \$$(DEP_$l.lib))"; \
echo "") >> $(LIB_DEP_FILE)
endif
ifneq ($(DEP_MISSING_PORTS),)
@(echo "MISSING_PORTS += $(DEP_MISSING_PORTS)"; \
echo "") >> $(LIB_DEP_FILE)
endif
@(echo "$(LIB).lib: check_ports $(addsuffix .lib,$(LIBS))"; \
echo " @\$$(MKDIR) -p \$$(LIB_CACHE_DIR)/$(LIB)"; \
echo " \$$(VERBOSE_MK)\$$(MAKE) $(VERBOSE_DIR) -C \$$(LIB_CACHE_DIR)/$(LIB) -f \$$(BASE_DIR)/mk/lib.mk \\"; \
echo " REP_DIR=$(REP_DIR) \\"; \
echo " LIB_MK=$(LIB_MK) \\"; \
echo " LIB=$(LIB) \\"; \
echo " DEPS=\"\$$(sort \$$($(DEP_VAR_NAME)))\" \\"; \
echo " BUILD_BASE_DIR=$(BUILD_BASE_DIR) \\"; \
echo " SHELL=$(SHELL) \\"; \
echo " SHARED_LIBS=\"\$$(SHARED_LIBS)\"\\"; \
echo " INSTALL_DIR=\$$(INSTALL_DIR)"; \
echo "") >> $(LIB_DEP_FILE)
@for i in $(LIBS_TO_VISIT); do \
$(MAKE) $(VERBOSE_DIR) -f $(BASE_DIR)/mk/dep_lib.mk REP_DIR=$(REP_DIR) LIB=$$i; done
ifdef SHARED_LIB
@(echo "SHARED_LIBS += $(LIB)"; \
echo "") >> $(LIB_DEP_FILE)
endif