Re: [Minios-devel] [UNIKRAFT PATCH 6/8] build/Makefile.rules: Add support for linker scripts requiring the pre-processor '*.ldS'

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

On 11.09.2018 18:12, Yuri Volchkov wrote:
> Hi,
>
> why to invent own naming. Why don't use names like are used in other
> famous projects. From linux/Documentation/kbuild/makefiles.txt:
>
>         When the vmlinux image is built, the linker script
>         arch/$(ARCH)/kernel/vmlinux.lds is used.
>         The script is a preprocessed variant of the file vmlinux.lds.S
>         located in the same directory.
>         kbuild knows .lds files and includes a rule *lds.S -> *lds.
>
> Also this patch looks incomplete. I propose to introduce the rule here
> already for the "lds.S -> lds".
What is incomplete?

If you prefer .lds.S, it is fine. I am not insisting on .ldS. There is 
no official standard defined, so better use something people are 
familiar with.
> And renaming plat/kvm/x86/link64.lds to plat/kvm/x86/link64.lds.S as Wei
> Chen did in the upcoming patch series also belongs here. Obviously that
> would require adding a signed-off with his name.
He introduced a new one for Arm64.

> And one last thing, this mechanism requires a bit more explanation in
> the comments (probably next to the build rule). It's a bit hard to
> understand what is happening here if you never met such thing before.
Fine. Let me do a v2 ;-)

> - Yuri.
>
> Simon Kuenzer <simon.kuenzer@xxxxxxxxx> writes:
>
> > Introduce support for linker scripts that have to be pre-processed. Such a 
> > linker
> > script source file has to have the file extension *.ldS. In order to generate
> >
> > Within a platforms' Linker.uk file, two Makefile functions are
> >
> > Called *.ldS, normal linker script is *.lds
> >
> > Usage example in a Linker.uk
> >
> >   MY_LDSCRIPT_SRC := $(CONFIG_UK_BASE)/plat/my/linker.ldS
> >   MY_LDSCRIPT     := $(call ldS2lds,libmyplat,$(KVM_LDSCRIPT_SRC))
> >
> >   # Install build rule for linker script
> >   $(eval $(call buildrule_ldS,libkvmplat,$(MY_LDSCRIPT_SRC),$(MY_LDSCRIPT)))
> >
> >   # Afterwards refer with $(MY_LDSCRIPT) to the generated linker script.
> >
> > Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> > ---
> >   support/build/Makefile.rules | 37 +++++++++++++++++++++++++++++++++++++
> >   1 file changed, 37 insertions(+)
> >
> > diff --git a/support/build/Makefile.rules b/support/build/Makefile.rules
> > index ebbb8dd..aad6942 100644
> > --- a/support/build/Makefile.rules
> > +++ b/support/build/Makefile.rules
> > @@ -78,6 +78,26 @@ obj2dep = $(patsubst %.o,%.d,$(1))
> >   # src2dep $libname,$source(s),$variant(optional)
> >   src2dep = $(call obj2dep,$(call src2obj,$(1),$(2),$(3)))
> >   
> > +# converts paths of linker script sources (*.ldS) to paths of corresponding
> > +# processed linker scripts (*.lds) within the build directory
> > +# ldS2lds $libname,$ldS(s),$variant(optional)
> > +define ldS2lds =
> > +$(if $(3),\
> > +$(addprefix $(call sub_build_dir,$(1))/,$(addsuffix .$(3).lds,$(basename 
> > $(notdir $(2))))),\
> > +$(addprefix $(call sub_build_dir,$(1))/,$(addsuffix .lds,$(basename $(notdir 
> > $(2)))))\
> > +)
> > +endef
> > +
> > +# converts paths of processed linker scripts (*.lds) to corresponding
> > +# dependency files
> > +# lds2dep $lds(s)
> > +lds2dep = $(addsuffix .d,$(1))
> > +
> > +# converts paths of linker script sources (*.ldS) to paths of corresponding
> > +# dependency files
> > +# ldS2dep $libname,$ldS(s),$variant(optional)
> > +ldS2dep = $(call lds2dep,$(call ldS2lds,$(1),$(2),$(3)))
> > +
> >   
> >   ################################################################################
> >   #
> > @@ -392,6 +412,23 @@ $(eval $(call vprefix_lib,$(1),OBJS-y) += $(3))
> >   $(eval $(call vprefix_lib,$(1),CLEAN-y) += $(call build_clean,$(3)) $(call 
> > obj2dep,$(3)))
> >   endef
> >   
> > +define buildrule_ldS =
> > +$(3): $(2) | prepare
> > +       $(call build_cmd_fixdep,LDS,$(1),$(3),\
> > +               $(AS)  -E -P -x assembler-with-cpp $(ASINCLUDES) 
> > $(ASINCLUDES-y) \
> > +                      $($(call vprefix_lib,$(1),ASINCLUDES)) $($(call 
> > vprefix_lib,$(1),ASINCLUDES-y)) \
> > +                      $(ASFLAGS) $(ASFLAGS-y) \
> > +                      $($(call vprefix_lib,$(1),ASFLAGS)) $($(call 
> > vprefix_lib,$(1),ASFLAGS-y)) \
> > +                      $(4) \
> > +                      -c $(2) -o $(3) $(depflags),\
> > +               $(call lds2dep,$(3))
> > +       )
> > +
> > +UK_SRCS-y += $(2)
> > +UK_DEPS-y += $(call lds2dep,$(3))
> > +$(eval $(call vprefix_lib,$(1),CLEAN-y) += $(call build_clean,$(3)) $(call 
> > lds2dep,$(3)))
> > +endef
> > +
> >   # wrapper for buildrule_*,
> >   # selects appropriate buildrule depending on file extension
> >   #
> > --
> > 2.7.4
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