[PATCH] Makefile: fix u-boot-initial-env target if lto is enabled

[Pali Rohár]

On Tuesday 18 October 2022 14:04:46 Tom Rini wrote:
> On Tue, Oct 18, 2022 at 08:03:31PM +0200, Pali Rohár wrote:
> > On Tuesday 18 October 2022 19:48:27 Max Krummenacher wrote:
> > > From: Max Krummenacher <max.krummenacher at toradex.com>
> > > 
> > > With LTO enabled the U-Boot initial environment is no longer stored
> > > in an easy accessible section in env/common.o. I.e. the section name
> > > changes from build to build, its content maybe compressed and it is
> > > annotated with additional data.
> > > 
> > > For GCC adding the option '-ffat-lto-objects' when compiling common.o
> > > adds additionally the traditional sections in the object file and
> > > 'make u-boot-initial-env' would work also for the LTO enabled case.
> > > However clang doesn't have that option.
> > > 
> > > Fix this by recompiling common.o into a object file only used for
> > > the creation of u-boot-initial-env if LTO is enabled.
> > > 
> > > See also:
> > > https://lore.kernel.org/all/927b122e-1f62-e790-f5ca-30bae4332c77@foss.st.com/
> > > 
> > > Signed-off-by: Max Krummenacher <max.krummenacher at toradex.com>
> > > 
> > > ---
> > > 
> > >  Makefile | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > > 
> > > diff --git a/Makefile b/Makefile
> > > index 3866cc62f9a..cd45c720d23 100644
> > > --- a/Makefile
> > > +++ b/Makefile
> > > @@ -2451,9 +2451,17 @@ endif
> > >  	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
> > >  
> > >  quiet_cmd_genenv = GENENV  $@
> > > +ifeq ($(LTO_ENABLE),y)
> > > +cmd_genenv = $(CC) $(filter-out $(LTO_CFLAGS),$(c_flags)) -c -o env/initial_env.o env/common.c; \
> > > +	$(OBJCOPY) --dump-section .rodata.default_environment=$@ env/initial_env.o; \
> > > +	sed --in-place -e 's/\x00/\x0A/g' $@; sed --in-place -e '/^\s*$$/d' $@; \
> > > +	sort --field-separator== -k1,1 --stable $@ -o $@; \
> > > +	rm -f env/initial_env.o env/initial_env.su
> > > +else
> > >  cmd_genenv = $(OBJCOPY) --dump-section .rodata.default_environment=$@ env/common.o; \
> > 
> > This code is still broken because in some cases section name is not RO.
> 
> Wait, when does that happen?
> 
> -- 
> Tom

E.g. for mvebu_espressobin-88f3720_defconfig