From: Sam Ravnborg The external module support recently introduced caused a number of problems: - To build an external module the Module.symvers file was needed - To create the Module.symvers file a module was required - If Module.symvers was missing kbuild boiled out with an error - If vmlinux was missing also the stage 2 of module build failed (make -k) - It was not documented what was needed to actually bauild a module The following patch addresses this by adding the following functionality: - Always generate the Module.symvers file - Ignore a missing Module.symvers file - Add a new target modules_prepare, it prepares the kernel for building external modules, and is also usefull with O= - And it adds some more comments to Makefile.modpost, so others may follow it with some luck - .modpost.cmd is no longer generated This should close all reports on issues with respect to building external modules with current kernel - which has been identified as kernel problems. --- 25-akpm/Makefile | 6 ++ 25-akpm/scripts/Makefile.modpost | 86 ++++++++++++++++++++++++++------------- 25-akpm/scripts/modpost.c | 7 +-- 3 files changed, 66 insertions(+), 33 deletions(-) diff -puN Makefile~kbuild-improved-external-module-support Makefile --- 25/Makefile~kbuild-improved-external-module-support Tue Apr 20 14:46:06 2004 +++ 25-akpm/Makefile Tue Apr 20 14:46:06 2004 @@ -716,8 +716,12 @@ modules: $(vmlinux-dirs) $(if $(KBUILD_B @echo ' Building modules, stage 2.'; $(Q)$(MAKE) -rR -f $(srctree)/scripts/Makefile.modpost -# Install modules +# Target to prepare building external modules +.PHONY: modules_prepare +modules_prepare: prepare-all scripts + +# Target to install modules .PHONY: modules_install modules_install: _modinst_ _modinst_post diff -puN scripts/Makefile.modpost~kbuild-improved-external-module-support scripts/Makefile.modpost --- 25/scripts/Makefile.modpost~kbuild-improved-external-module-support Tue Apr 20 14:46:06 2004 +++ 25-akpm/scripts/Makefile.modpost Tue Apr 20 14:46:06 2004 @@ -1,34 +1,71 @@ # =========================================================================== # Module versions # =========================================================================== +# +# Stage one of module building created the following: +# a) The individual .o files used for the module +# b) A .o file wich is the .o files above linked together +# c) A .mod file in $(MODVERDIR)/, listing the name of the +# the preliminary .o file, plus all .o files + +# Stage 2 is handled by this file and does the following +# 1) Find all modules from the files listed in $(MODVERDIR)/ +# 2) modpost is then used to +# 3) create one .mod.c file pr. module +# 4) create one Module.symvers file with CRC for all exported symbols +# 5) compile all .mod.c files +# 6) final link of the module to a file + +# Step 3 is used to place certain information in the module's ELF +# section, including information such as: +# Version magic (see include/vermagic.h for full details) +# - Kernel release +# - SMP is CONFIG_SMP +# - PREEMPT is CONFIG_PREEMPT +# - GCC Version +# Module info +# - Module version (MODULE_VERSION) +# - Module alias'es (MODULE_ALIAS) +# - Module license (MODULE_LICENSE) +# - See include/linux/module.h for more details + +# Step 4 is solely used to allow module versioning in external modules, +# where the CRC of each module is retreived from the Module.symers file. -.PHONY: __modversions -__modversions: +.PHONY: _modpost +_modpost: __modpost include .config include scripts/Makefile.lib -# +symverfile := $(objtree)/Module.symvers +# Step 1), find all modules listed in $(MODVERDIR)/ __modules := $(shell head -q -n1 /dev/null $(wildcard $(MODVERDIR)/*.mod)) -modules := $(patsubst %.o,%.ko,$(wildcard $(__modules:.ko=.o))) +modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o))) -__modversions: $(modules) - @: +_modpost: $(modules) -# The final module link -quiet_cmd_ld_ko_o = LD [M] $@ - cmd_ld_ko_o = $(LD) $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ \ - $(filter-out FORCE,$^) +# Step 2), invoke modpost +# Includes step 3,4 +quiet_cmd_modpost = MODPOST + cmd_modpost = scripts/modpost \ + $(if $(KBUILD_EXTMOD),-i,-o) $(symverfile) \ + $(filter-out FORCE,$^) -$(modules): %.ko :%.o %.mod.o FORCE - $(call if_changed,ld_ko_o) +.PHONY: __modpost +__modpost: $(wildcard vmlinux) $(modules:.ko=.o) FORCE + $(call cmd,modpost) + +# Declare generated files as targets for modpost +$(symverfile): __modpost ; +$(modules:.ko=.mod.c): __modpost ; -targets += $(modules) -# Compile version info for unresolved symbols +# Step 5), compile all *.mod.c files +# modname is set to make c_flags define KBUILD_MODNAME modname = $(*F) quiet_cmd_cc_o_c = CC $@ @@ -40,23 +77,16 @@ $(modules:.ko=.mod.o): %.mod.o: %.mod.c targets += $(modules:.ko=.mod.o) -# All the .mod.c files are generated using the helper "modpost" - -.PHONY: __modpost - -$(modules:.ko=.mod.c): __modpost ; - -# Extract all checksums for all exported symbols +# Step 6), final link of the modules +quiet_cmd_ld_ko_o = LD [M] $@ + cmd_ld_ko_o = $(LD) $(LDFLAGS) $(LDFLAGS_MODULE) -o $@ \ + $(filter-out FORCE,$^) -quiet_cmd_modpost = MODPOST - cmd_modpost = scripts/modpost \ - $(if $(filter vmlinux,$^),-o,-i) $(objtree)/Module.symvers \ - $(filter-out FORCE,$^) +$(modules): %.ko :%.o %.mod.o FORCE + $(call if_changed,ld_ko_o) -__modpost: $(if $(KBUILD_EXTMOD),,$(wildcard vmlinux)) $(modules:.ko=.o) FORCE - $(call if_changed,modpost) +targets += $(modules) -targets += __modpost # Add FORCE to the prequisites of a target to force it to be always rebuilt. # --------------------------------------------------------------------------- diff -puN scripts/modpost.c~kbuild-improved-external-module-support scripts/modpost.c --- 25/scripts/modpost.c~kbuild-improved-external-module-support Tue Apr 20 14:46:06 2004 +++ 25-akpm/scripts/modpost.c Tue Apr 20 14:46:06 2004 @@ -625,10 +625,9 @@ read_dump(const char *fname) void *file = grab_file(fname, &size); char *line; - if (!file) { - perror(fname); - abort(); - } + if (!file) + /* No symbol versions, silently ignore */ + return; while ((line = get_next_line(&pos, file, size))) { char *symname, *modname, *d; _