| Message ID | 20140216203724.GA19216@ravnborg.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Feb 16, 2014 at 09:37:24PM +0100, Sam Ravnborg wrote: > The trick used is that for each directory a linker script is > generated that name all the file to be linked - and for > sub-directories this is just the linker script for that directory. > > The file continue to be named "built-in.o" but it is really a linker script. You'll need binutils newer than 2012-06-25 https://sourceware.org/ml/binutils/2012-06/msg00201.html > I recall the idea is from someone else - but have long lost memory of > from where I saw it. I think it might have been my idea originally, implemented by Stephen Rothwell. Another possibility is to use thin archives to package up the objects. Thin archives are like normal archives except they just contain paths to the objects, not the object contents. Paths are flattened when adding one thin archive to another. I think Stephen may have tried that idea too.
On Wed, Feb 19, 2014 at 01:28:56AM +1030, Alan Modra wrote: > On Sun, Feb 16, 2014 at 09:37:24PM +0100, Sam Ravnborg wrote: > > The trick used is that for each directory a linker script is > > generated that name all the file to be linked - and for > > sub-directories this is just the linker script for that directory. > > > > The file continue to be named "built-in.o" but it is really a linker script. > > You'll need binutils newer than 2012-06-25 > https://sourceware.org/ml/binutils/2012-06/msg00201.html > > > I recall the idea is from someone else - but have long lost memory of > > from where I saw it. > > I think it might have been my idea originally, implemented by Stephen > Rothwell. Sounds right - added in cc: > > Another possibility is to use thin archives to package up the objects. > Thin archives are like normal archives except they just contain paths > to the objects, not the object contents. Paths are flattened when > adding one thin archive to another. I think Stephen may have tried > that idea too. I just coded this in a similar simple fashion. It broke building vdso - needs to look into that and will get back when I may understand why my link suddenly broke. Thanks for the feedback! Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Feb 18, 2014 at 10:48:01PM +0100, Sam Ravnborg wrote: > > Another possibility is to use thin archives to package up the objects. > > Thin archives are like normal archives except they just contain paths > > to the objects, not the object contents. Paths are flattened when > > adding one thin archive to another. I think Stephen may have tried > > that idea too. > I just coded this in a similar simple fashion. > It broke building vdso - needs to look into that and will get back when I may > understand why my link suddenly broke. Missing --whole-archive?
On Wed, Feb 19, 2014 at 11:31:00AM +1030, Alan Modra wrote: > On Tue, Feb 18, 2014 at 10:48:01PM +0100, Sam Ravnborg wrote: > > > Another possibility is to use thin archives to package up the objects. > > > Thin archives are like normal archives except they just contain paths > > > to the objects, not the object contents. Paths are flattened when > > > adding one thin archive to another. I think Stephen may have tried > > > that idea too. > > I just coded this in a similar simple fashion. > > It broke building vdso - needs to look into that and will get back when I may > > understand why my link suddenly broke. > > Missing --whole-archive? No - at least something else to begin with. A special liker script is used when building the vdsp files for x86 - and the linker script is ignored as such when embedded in a .o file with ar it seems. This is not a big suprise. The makefile magic used for the vdso part of the kernel needs a bit more coffee than what is good for me for now... Will look at it again later. Thanks for the feedback. Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index a48abea..b6ca48a 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -249,14 +249,6 @@ config DEBUG_SECTION_MISMATCH the analysis would not catch the illegal reference. This option tells gcc to inline less (but it does result in a larger kernel). - - Run the section mismatch analysis for each module/built-in.o file. - When we run the section mismatch analysis on vmlinux.o, we - lose valueble information about where the mismatch was - introduced. - Running the analysis for each module/built-in.o file - tells where the mismatch happens much closer to the - source. The drawback is that the same mismatch is - reported at least twice. - Enable verbose reporting from modpost in order to help resolve the section mismatches that are reported. diff --git a/scripts/Makefile.build b/scripts/Makefile.build index d5d859c..a568276 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -158,11 +158,6 @@ ifneq ($(KBUILD_CHECKSRC),0) endif endif -# Do section mismatch analysis for each module/built-in.o -ifdef CONFIG_DEBUG_SECTION_MISMATCH - cmd_secanalysis = ; scripts/mod/modpost $@ -endif - # Compile C sources (.c) # --------------------------------------------------------------------------- @@ -378,10 +373,9 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ; ifdef builtin-target quiet_cmd_link_o_target = LD $@ # If the list of objects to link is empty, just create an empty built-in.o -cmd_link_o_target = $(if $(strip $(obj-y)),\ - $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \ - $(cmd_secanalysis),\ - rm -f $@; $(AR) rcs$(KBUILD_ARFLAGS) $@) +cmd_link_o_target = $(if $(filter $(obj-y), $^), \ + echo INPUT\($(filter $(obj-y), $^)\) > $@, \ + echo "/* empty */" > $@) $(builtin-target): $(obj-y) FORCE $(call if_changed,link_o_target) @@ -428,10 +422,10 @@ $($(subst $(obj)/,,$(@:.o=-objs))) \ $($(subst $(obj)/,,$(@:.o=-y)))), $^) quiet_cmd_link_multi-y = LD $@ -cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis) +cmd_link_multi-y = echo INPUT\($(link_multi_deps)\) > $@ quiet_cmd_link_multi-m = LD [M] $@ -cmd_link_multi-m = $(cmd_link_multi-y) +cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) # We would rather have a list of rules like # foo.o: $(foo-objs)