Re: [Minios-devel] [PATCH 1/2] Makefile.uk: Fix link issues on arm64

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Hi Justin,

Please see inline.

On 12/19/19 11:23 AM, Jia He wrote:
> Without this patch, when starting helloworld app with newlib on arm
> kvm plat, it will report a link error as follows:
> iapps/helloworld.newlib/build/helloworld_kvm-arm64.o: In function `wcstold_l':
> apps/helloworld.newlib/build/libnewlibc/origin/newlib-2.5.0.20170922/newlib/libc/stdlib/wcstold.c:77:
>  undefined reference to `strtold_l'
> apps/helloworld.newlib/build/libnewlibc/origin/newlib-2.5.0.20170922/newlib/libc/stdlib/wcstold.c:77:(.text+0x7c4e4):
>  relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol 
> `strtold_l'
> 
> I once did configure and build of newlib from uptream, this macro is
> defined on my Thunderx2 armv8a server (Unbuntu 18.04 + gcc version 7.4.0)
> 
> Signed-off-by: Jia He <justin.he@xxxxxxx>
> ---
>  Makefile.uk | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile.uk b/Makefile.uk
> index 17d8d7a..54efe1a 100644
> --- a/Makefile.uk
> +++ b/Makefile.uk
> @@ -85,9 +85,9 @@ LIBNEWLIB_GLOBAL_FLAGS-y  += -DMISSING_SYSCALL_NAMES 
> -DMALLOC_PROVIDED
>  LIBNEWLIB_GLOBAL_FLAGS-y  += -D_POSIX_REALTIME_SIGNALS
>  LIBNEWLIB_GLOBAL_FLAGS-$(CONFIG_LIBNEWLIBC_WANT_IO_C99_FORMATS) += 
> -D_WANT_IO_C99_FORMATS
>  LIBNEWLIB_GLOBAL_FLAGS-$(CONFIG_LIBNEWLIBC_LINUX_ERRNO_EXTENSIONS) += 
> -D__LINUX_ERRNO_EXTENSIONS__
> +LIBNEWLIB_GLOBAL_FLAGS-y  += -D_HAVE_LONG_DOUBLE

I don't think it's safe to define this for all architectures. Besides
that, when I introduced this flag I didn't check whether this is
actually true, i.e. whether sizeof(double) and sizeof(long double) are
the same. And they are not, sizeof(double) == 8 while sizeof(long
double) == 16. Therefore we have to force the compiler to make them
equal in size using `-mlong-double-64` (this means updating global
CFLAGS and CXXFLAGS).

Now, my question to you is: do these 2 types have the same size? Even if
they have, you should set this flag only for your architecture. If not,
can you force the compiler to make the equal in size?

>  ifeq ($(CONFIG_ARCH_X86_64),y)
>  LIBNEWLIB_GLOBAL_FLAGS-y  += -D_LDBL_EQ_DBL
> -LIBNEWLIB_GLOBAL_FLAGS-y  += -D_HAVE_LONG_DOUBLE
>  endif
>  
>  CFLAGS-y   += $(LIBNEWLIB_GLOBAL_FLAGS-y)
> 

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