Re: Linker question

[Sascha Hauer <s.hauer@pengutronix.de>]

Hi Franck,

On Wed, Dec 14, 2011 at 12:14:08AM +0100, Franck JULLIEN wrote:
> Hi,
> 
> I'm doing some tests with the openrisc processor. As I'm building
> barebox I have a question
> related to the linking of barebox.
> 
> In order to get uint64 arithmetic functions, I need to add "-L $(shell
> dirname `$(CC) $(CFLAGS) -print-libgcc-file-name`) -lgcc"
> to the final link (only way ? found this in uboot).
> 
> However, if I do this using LDFLAGS_barebox I get :
> 
> /opt/crosstool/or32/or32-elf/bin/or32-elf-ld  -Map barebox.map -L
> /opt/crosstool/or32/or32-elf-1.0rc1/bin/../lib/gcc/or32-elf/4.5.1-or32-1.0rc4
> -lgcc -o barebox -T arch/openrisc/cpu/barebox.lds  --start-group
> common/built-in.o  drivers/built-in.o  commands/built-in.o
> lib/built-in.o  crypto/built-in.o  net/built-in.o  fs/built-in.o
> arch/openrisc/boards/generic/built-in.o  arch/openrisc/lib/built-in.o
> arch/openrisc/cpu/built-in.o --end-group
> 
> And it doesn't work. It works if "-L
> /opt/crosstool/or32/or32-elf-1.0rc1/bin/../lib/gcc/or32-elf/4.5.1-or32-1.0rc4
> -lgcc" is at the end of the command line:
> 
> /opt/crosstool/or32/or32-elf/bin/or32-elf-ld -Map barebox.map -o
> barebox -T arch/openrisc/cpu/barebox.lds --start-group
> common/built-in.o  drivers/built-in.o  commands/built-in.o
> lib/built-in.o  crypto/built-in.o  net/built-in.o  fs/built-in.o
> arch/openrisc/boards/generic/built-in.o  arch/openrisc/lib/built-in.o
> arch/openrisc/cpu/built-in.o --end-group -L
> /opt/crosstool/or32/or32-elf-1.0rc1/bin/../lib/gcc/or32-elf/4.5.1-or32-1.0rc4
> -lgcc
> 
> Any idea on why this is happening ?
> 
> The only way I found to fix this is to move LDFLAGS_barebox in the
> main Makefile:
> 
> -      cmd_barebox__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_barebox) -o $@ \
> +      cmd_barebox__ ?= $(LD) $(LDFLAGS)  -o $@ \
>        -T $(barebox-lds) $(barebox-head)                         \
> -      --start-group $(barebox-common) --end-group                  \
> +      --start-group $(barebox-common) --end-group $(LDFLAGS_barebox)
>                \
>        $(filter-out $(barebox-lds) $(barebox-common) FORCE ,$^)
> 
> What do you think about this problem ?

The kernel currently does it the same way for openrisc. The other
architectures have there own implementation of the 64bit arithmetix
functions inside the kernel (and barebox) which is IMO cleaner. Maybe
you can grab them from the gcc source code and use them in barebox
instead.

Sascha

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