Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx> writes:
> On Wed, 2023-02-01 at 11:00 +0100, Marc Hartmayer wrote:
>> Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx> writes:
>>
>> > On Thu, 2023-01-19 at 12:40 +0100, Marc Hartmayer wrote:
>> > > Use the C pre-processor for the linker script generation. For example,
>> > > this enables us the use of constants in the "linker scripts" `*.lds.S`.
>> > >
>> > > Signed-off-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
>> > > ---
>> > > .gitignore | 1 +
>> > > s390x/Makefile | 6 ++++--
>> > > s390x/{flat.lds => flat.lds.S} | 0
>> > > s390x/snippets/asm/{flat.lds => flat.lds.S} | 0
>> > > s390x/snippets/c/{flat.lds => flat.lds.S} | 0
>> > > 5 files changed, 5 insertions(+), 2 deletions(-)
>> > > rename s390x/{flat.lds => flat.lds.S} (100%)
>> > > rename s390x/snippets/asm/{flat.lds => flat.lds.S} (100%)
>> > > rename s390x/snippets/c/{flat.lds => flat.lds.S} (100%)
>> > >
>> > > diff --git a/.gitignore b/.gitignore
>> > > index 601822d67325..29f352c5ceb6 100644
>> > > --- a/.gitignore
>> > > +++ b/.gitignore
>> > > @@ -31,3 +31,4 @@ cscope.*
>> > > /s390x/comm.key
>> > > /s390x/snippets/*/*.hdr
>> > > /s390x/snippets/*/*.*obj
>> > > +/s390x/**/*.lds
>> > > diff --git a/s390x/Makefile b/s390x/Makefile
>> > > index 8719f0c837cf..44ccca8102d6 100644
>> > > --- a/s390x/Makefile
>> > > +++ b/s390x/Makefile
>> > > @@ -76,7 +76,7 @@ CFLAGS += -fno-delete-null-pointer-checks
>> > > LDFLAGS += -nostdlib -Wl,--build-id=none
>> > >
>> > > # We want to keep intermediate files
>> > > -.PRECIOUS: %.o
>> > > +.PRECIOUS: %.o %.lds
>> > >
>> > > asm-offsets = lib/$(ARCH)/asm-offsets.h
>> > > include $(SRCDIR)/scripts/asm-offsets.mak
>> > > @@ -159,6 +159,8 @@ $(SNIPPET_DIR)/c/%.gbin: $(SNIPPET_DIR)/c/%.o $(snippet_lib) $(FLATLIBS) $(SNIPP
>> > > %.hdr.obj: %.hdr
>> > > $(OBJCOPY) -I binary -O elf64-s390 -B "s390:64-bit" $< $@
>> > >
>> > > +%.lds: %.lds.S
>> > > + $(CPP) $(autodepend-flags) $(CPPFLAGS) -P -C -o $@ $<
>> >
>> > Where is CPP defined?
>> > Do you need the $(autodepend-flags)? It generates a rule with target flat.lds.o.
>> ^^^^^^^^^^
>>
>> Where does it generate a new Makefile rule? It generates the dependency
>> file used for the dependency tracking with the name: .flat.lds.S.d (or
>> similar)
>
> Yes and that file contains the rule.
> cat s390x/.flat.d
> flat.lds.o: /foo/bar/s390x/flat.lds.S \
> /foo/bar/lib/asm/asm-offsets.h \
> /foo/bar/lib/generated/asm-offsets.h
>
>>
>> > I don't think that would be used anywhere.
>>
>> It’s used for the dependency tracking. See line
>>
>> $KUT/Makefile:122
>>
>> -include */.*.d */*/.*.d
>
> Indeed, but the target flat.lds.o isn't used anywhere, is it?
> So if flat.lds.S included some other header and that changed,
> flat.lds wouldn't be rebuild.
> So you would either need to generate a rule with flat.lds as target
> or make it depend on flat.lds.o somehow.
>
>>
>> > In the next patch you add $(asm-offsets) as a prerequisite, if the generated rule would
>> > be effective, you wouldn't need that, would you?
>>
>> I thought, $(asm-offsets) is used to make sure that the file
>> <asm/asm-offsets.h> is generated.
>
> I was asking if this is necessary, since s390x/.flat.d contains the asm-offset headers
> as prerequisites. So if the dependency file is included, the headers will be build,
> but I guess that this is circular, in order to generate the dependencies,
> the asm-offset headers must already have been built.
Hmm, no, this won’t work unless the dependency file was already created
(chicken-egg problem). That’s probably the reason for this Makefile
rule:
generated-files = $(asm-offsets)
$(tests:.elf=.o) $(asmlib) $(cflatobjs): $(generated-files)
>>
>> […snip]
>>
>
--
Kind regards / Beste Grüße
Marc Hartmayer
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Gregor Pillen
Geschäftsführung: David Faller
Sitz der Gesellschaft: Böblingen
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