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5ae0dab6c5
This patch removes the implicit build of all shared libraries a target depends on. Targets only depend on the respective ABIs instead. This alleviates the need to locally build complex shared libraries (think of Qt) when developing applications. Instead, application developers can use binary depot archives. The implementation splits the mk/lib.mk file into three files: - mk/a.mk for building one static library (.lib.a) - mk/so.mk for building one shared object (.lib.so) - mk/abi.mk for building one ABI stub (.abi.so) Furthermore, the commit moves messages and the collection of build artifacts to var/libdeps, triggers the build of kernel-specific ld-<kernel>.lib.so, and prunes the lib-dependency tree at ABIs. Fixes #5061
99 lines
3.7 KiB
Makefile
99 lines
3.7 KiB
Makefile
##
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## Create an ABI stub named '<lib>.abi.so'
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##
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## Invoked from the library's build directory within the lib cache.
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## The following variables must be passed when calling this file:
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##
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## BASE_DIR - base directory of the build system
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## VERBOSE - build verboseness modifier
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## LIB_CACHE_DIR - library build cache location
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## LIB - library name
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## SYMBOLS - path of symbols file
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## SPECS - build specs (i.e., CPU architecture)
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##
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#
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# An ABI-stub library does not contain any code or data but only the symbol
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# information of the binary interface (ABI) of the shared library.
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#
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# The ABI stub is linked by the users of the library (executables or shared
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# objects) instead of the real library. This effectively decouples the library
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# users from the concrete library instance but binds them merely to the
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# library's binary interface. Note that the ABI stub is not used at runtime at
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# all. At runtime, the real library that implements the ABI is loaded by the
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# dynamic linker.
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#
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# The symbol information are incorporated into the ABI stub via an assembly
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# file named 'symbols.s' that is generated from the library's symbol list.
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#
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ABI_SO := $(addsuffix .abi.so,$(LIB))
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SYMBOLS := $(wildcard $(SYMBOLS))
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ifeq ($(SYMBOLS),)
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all:
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else
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all: $(ABI_SO)
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endif
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include $(BASE_DIR)/mk/util.inc
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include $(SPEC_FILES)
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include $(BASE_DIR)/mk/global.mk
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include $(BASE_DIR)/mk/generic.mk
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#
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# Generate assembler file from symbol list
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#
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# For undefined symbols (type U), we create a hard dependency by referencing
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# the symbols from the assembly file. The reference is created in the form of
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# a '.long' value with the address of the symbol. On x86_64, this is not
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# possible for PIC code. Hence, we reference the symbol via a PIC-compatible
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# movq instruction instead.
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#
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# If we declared the symbol as '.global' without using it, the undefined symbol
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# gets discarded at link time unless it is directly referenced by the target.
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# This is a problem in situations where the undefined symbol is resolved by an
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# archive rather than the target. I.e., when linking posix.lib.a (which
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# provides 'Libc::Component::construct'), the 'construct' function is merely
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# referenced by the libc.lib.so's 'Component::construct' function. But this
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# reference apparently does not suffice to keep the posix.lib.a's symbol. By
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# adding a hard dependency, we force the linker to resolve the symbol and don't
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# drop posix.lib.a.
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#
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ASM_SYM_DEPENDENCY := .long \1
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ifeq ($(filter-out $(SPECS),x86_64),)
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ASM_SYM_DEPENDENCY := movq \1@GOTPCREL(%rip), %rax
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endif
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symbols.s: $(SYMBOLS)
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$(MSG_CONVERT)$@
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$(VERBOSE)\
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sed -e "s/^\(\w\+\) D \(\w\+\)\$$/.data; .global \1; .type \1,%object; .size \1,\2; \1: .skip 1/" \
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-e "s/^\(\w\+\) V/.data; .weak \1; .type \1,%object; \1: .skip 1/" \
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-e "s/^\(\w\+\) T/.text; .global \1; .type \1,%function; \1:/" \
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-e "s/^\(\w\+\) R \(\w\+\)\$$/.section .rodata; .global \1; .type \1,%object; .size \1,\2; \1:/" \
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-e "s/^\(\w\+\) W/.text; .weak \1; .type \1,%function; \1:/" \
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-e "s/^\(\w\+\) B \(\w\+\)\$$/.bss; .global \1; .type \1,%object; .size \1,\2; \1:/" \
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-e "s/^\(\w\+\) U/.text; .global \1; $(ASM_SYM_DEPENDENCY)/" \
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$< > $@
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#
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# The '.PRECIOUS' special target prevents make to remove the intermediate
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# assembler file. Otherwise make would spill the build log with messages
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# like "rm libc.symbols.s".
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#
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.PRECIOUS: symbols.s
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ABI_SONAME := $(addsuffix .lib.so,$(LIB))
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all: # prevent 'Nothing to be done' message
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@true
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$(ABI_SO): symbols.o
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$(MSG_MERGE)$(ABI_SO)
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$(VERBOSE)$(LD) -o $(ABI_SO) -soname=$(ABI_SONAME) -shared --eh-frame-hdr $(LD_OPT) \
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-T $(LD_SCRIPT_SO) \
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--whole-archive --start-group \
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$(LIB_SO_DEPS) $< \
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--end-group --no-whole-archive
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