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

[Yuri Volchkov <yuri.volchkov@xxxxxxxxx>]

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".

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.

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.

- 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
>

-- 
Yuri Volchkov
Software Specialist

NEC Europe Ltd
Kurfürsten-Anlage 36
D-69115 Heidelberg

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