Re: [Xenomai-core] [PATCH]Build xenomai on Blackfin in FDPIC format

[Philippe Gerum <rpm@xenomai.org>]

On Tue, 2006-11-14 at 11:32 +0800, Li Yi (Adam) wrote:
> Hi Philippe,
> 
> Since bfin-gcc release 2006-R1, bfin-gcc begins to support "FDPIC"
> format besides "BFLT".
> "FDPIC" supports shared library. Bellow patch makes it possible to
> build xenomai-2.2.5 in FDPIC
> format. In docs.blackfin.uclinux.org/doku.php?id=adeos there is step
> by step guide.
> 
> Although it is still possible to build xenomai as BFLT in this way: 
> 
> configure --host=bfin CC=bfin-uclinux-gcc LDFLAGS=-Wl,-elf2flt
> --disable-shared
> 
> There will be error:
> 
>  bfin-uclinux-gcc -Wl,-elf2flt -o cyclictest
> -Wl,@/home/adam/workspace/xenomai/xenomai_src/xenomai-
> 2.2.5/src/skins/posix/posix.wrappers
> cyclictest-cyclictest.o  ../../skins/posix/.libs/libpthread_rt.a
> -lpthread -lrt
> /home/adam/workspace/toolchain/1110/bfin-uclinux/bin/../lib/gcc/bfin-uclinux/4.1.1/../../../../bfin-uclinux/lib/libpthread.a( specific.o): In function `_pthread_key_delete':
> (.text+0x24e): undefined reference to `___wrap_pthread_mutex_lock'
> /home/adam/workspace/toolchain/1110/bfin-uclinux/bin/../lib/gcc/bfin-uclinux/4.1.1/../../../../bfin-uclinux/lib/libpthread.a( specific.o): In function `_pthread_key_delete':
> 
> And this can be fixed like:
> 
> bfin-uclinux-gcc -Wl,-elf2flt -o cyclictest
> -Wl,@/home/adam/workspace/xenomai/xenomai_src/xenomai-2.2.5/src/skins/posix/posix.wrappers cyclictest-cyclictest.o -lpthread -lrt ../../skins/posix/.libs/libpthread_rt.a
> 

As Gilles pointed out, we probably need a two steps link process here;
fiddling with the object ordering won't solve the library
inter-dependencies properly.

> But using "FDPIC" format is suggested.
> 

We'll move to FDPIC. No need to stick with a limitation on shared
objects, which additionally requires a two step building process for
working around chicken-and-eggs linking issues.

> Thanks,
> 
> -Yi
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-- 
Philippe.