[U-Boot] [PATCH 1/1] spl: u-boot-spl-nodtb.bin: remove .got and .got.plt sections

[Dr. Philipp Tomsich]

> On 12 Sep 2017, at 00:40, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> 
> For qemu-x86_64_defconfig on Debian Stretch
> ld 2.28 creates a .got and a .got.plt section in
> u-boot-spl.
> 
> If we do not ignore these sections objcopy generates an
> u-boot-spl-nodtb.bin file of 4 GiB which leads to
> subsequent failure of the build process.
> 
> According to
> https://sourceware.org/bugzilla/show_bug.cgi?id=22120#c2
> objcopy can not generate files with holes.
> 
> With the patch we can run qemu with the generated u-boot.rom.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> I ran the Travis CI tests with no error reported:
> https://travis-ci.org/xypron2/u-boot/builds/274042004
> 
> It is unclear to me why on Debian Stretch the .got and .got.plt sections
> are generated. The problem does not exist on Debian Jessie which uses
> binutils 2.25.
> 
> I found this comment in the BFD code which describes under which
> circumstances the .got.plt section is not generated:
> 
> https://sourceware.org/viewvc/src/bfd/elf64-x86-64.c?view=markup#l2921
> 
> Don't allocate .got.plt section if there are no GOT nor PLT
> entries and there is no reference to _GLOBAL_OFFSET_TABLE_.
> ---
> scripts/Makefile.spl | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
> index dd8065d87d..3b2d79d562 100644
> --- a/scripts/Makefile.spl
> +++ b/scripts/Makefile.spl
> @@ -286,7 +286,8 @@ quiet_cmd_objcopy = OBJCOPY $@
> cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
> 
> OBJCOPYFLAGS_$(SPL_BIN)-nodtb.bin = $(SPL_OBJCFLAGS) -O binary \
> -		$(if $(CONFIG_SPL_X86_16BIT_INIT),-R .start16 -R .resetvec)
> +		$(if $(CONFIG_SPL_X86_16BIT_INIT), \
> +		-R .start16 -R .resetvec -R .got -R .got.plt)

If there is a non-empty .got, it can not be safely removed. The remaining code
can (and will) reference data within the .got.
Did you check the contents of the .got and where these are referenced from?

> 
> $(obj)/$(SPL_BIN)-nodtb.bin: $(obj)/$(SPL_BIN) FORCE
> 	$(call if_changed,objcopy)
> -- 
> 2.11.0
>