[yocto] btrfs-tools Requires libgcc_s.so.1

[Marcelo E. Magallon]

On Thu, Mar 08, 2018 at 03:16:44PM -0600, Mark Hatle wrote:

>RDEPENDS are automatically promoted to DEPENDS (build-time).  I would normally
>expect libgcc_s.so.1 to be present via the typical default depends.  Does your
>recipe have an INHIBIT_DEFAULT_DEPENDS (I think that is it?) defined?  If so,
>you would need to manually add all build dependencies then.

INHIBIT_DEFAULT_DEPS.

No, it doesn't, but that's a good hint.

>An executable or library with a stated library dependency (soname) will
>automatically get an RDEPENDS.  The only time you should have to do an
>RDEPENDS_${PN} of a library is when that library is 'dlopened'.  (This is the
>case for things like pam modules.)

This is also the case in this situation.

glibc has this bit of code in pthread_cancel_init:

	  handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN);
	
	  if (handle == NULL
	      || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL
	      || (personality = __libc_dlsym (handle, "__gcc_personality_v0")) == NULL
	      || (forcedunwind = __libc_dlsym (handle, "_Unwind_ForcedUnwind"))
		 == NULL
	      || (getcfa = __libc_dlsym (handle, "_Unwind_GetCFA")) == NULL
	#ifdef ARCH_CANCEL_INIT
	      || ARCH_CANCEL_INIT (handle)
	#endif
	      )
	    __libc_fatal (LIBGCC_S_SO " must be installed for pthread_cancel to work\n");

it's dlopen()ing libgcc_s.so.1 in order to get thread 
cancellation to work via exception unwinding.

In my case, libgcc_s.so.1 is installed in the image before adding 
the RDEPENDS.

What doesn't make sense to me is why in both the OP's and my 
case, adding RDEPENDS_${PN} += "libgcc" is fixing anything. As 
you said, this is promoted to a DEPENDS, so libgcc is available 
at compile time, but that shouldn't change anything that I can 
see.

Thanks for looking at this,

Marcelo