Re: cross compile dietlibc (on x86_64 for arm)

Hi,

thank you for the answer,

> On January 24, 2018 at 10:21 AM Felix von Leitner <[email protected]> wrote:
> 
> 
> > I'm trying to cross compile dietlibc for arm:
> 
> > # make ARCH=arm CROSS="arm-cortexa15-linux-gnueabihf-" EXTRACFLAGS="-O2 -Wall -march=armv7-a -mfloat-abi=hard -mfpu=neon-vfpv4 -mabi=aapcs-linux -mtune=cortex-a15 -fno-stack-protector -std=gnu99" all
> > ...
> > ...
> > bin-x86_64/diet arm-cortexa15-linux-gnueabihf-gcc -D__dietlibc__ -pipe -nostdinc -D_REENTRANT -O2 -Wall -march=armv7-a -mfloat-abi=hard -mfpu=neon-vfpv4 -mabi=aapcs-linux -mtune=cortex-a15 -fno-stack-protector -std=gnu99 -O2 -fomit-frame-pointer -fstrict-aliasing -O0 -g -Wall -march=armv7-a -mfloat-abi=hard -mfpu=neon-vfpv4 -mabi=aapcs-linux -mtune=cortex-a15 -fno-stack-protector -std=gnu99 -W -Wall -Wextra -Wchar-subscripts -Wmissing-prototypes -Wmissing-declarations -Wno-switch -Wno-unused -Wredundant-decls -Wshadow -o bin-arm/elftrunc contrib/elftrunc.c
> > make[4]: bin-x86_64/diet: Command not found
> > make[4]: *** [Makefile:352: bin-arm/elftrunc] Error 127
> 
> > The failing make target is in the root Makefile:
> 
> > ...
> > $(OBJDIR)/elftrunc: $(OBJDIR)/diet contrib/elftrunc.c
> > 	bin-$(MYARCH)/diet $(CCC) $(CFLAGS) -o $@ contrib/elftrunc.c
> > ...
> 
> > here $(OBJDIR)/elftrunc depends on $(OBJDIR)/diet but in the recipe bin-$(MYARCH)/diet
> > is used.
> 
> > Do I have to build the dietlibc src tree natively first and then cross ?
> 
> Yes and no.
> At this point the library itself has already been built.
> So you can start cross-compiling dietlibc binaries with it.
> 
> However, for convenience, you'd probably want to use the diet binary for
> that, which you'd need in a version for the build host architecture to
> run it. So I recommend building a native dietlibc, too, so you can use
> its diet wrapper program.
> 
Actually I already compile/install dietlibc natively before cross compiling it,
say under the prefix '/tmp/my_prj/native/opt/diet';
the problem is I cannot use the 'diet' there because it is installed under the BINDIR
'...opt/diet/bin' and not '.../opt/diet/bin-x86_64'.

Anyway, this is just a little inconvenience as long as it's OK to build two different
versions of the lib in the same tree.
My current solution is:

# make EXTRACFLAGS="-O2 -Wall -march=native" all
# make ARCH=arm CROSS="arm-cortexa15-linux-gnueabihf-" EXTRACFLAGS="-O2 -Wall -march=armv7-a -mfloat-abi=hard -mfpu=neon-vfpv4 -mabi=aapcs-linux -mtune=cortex-a15 -fno-stack-protector -std=gnu99" all install