[yocto] [poky] Is this a bug of binutils

[Li Zhijian]

Hi，Laurentiu

I think it could be something wrong with binutils(2.23.1 or later)
there is different behavior at binutils-2.23.1/ld/ldfile.c（ldfile_open_file_search) from binutils-2.22

If both --sysroot directory and -L directory include libc.so , ld don't work
In my case， there are double libc.so(/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-poky-linux/usr/lib/libc.so and tmp/sysroots/qemux86-64/usr/lib/libc.so)

ld will link tmp/sysroots/qemux86-64/usr/lib/libc.so（ld always searchs -L directory at first)
then link /lib/libc.so.6 specified at tmp/sysroots/qemux86-64/usr/lib/libc.so instead of
append sysroot directory path before /lib/libc.so.6

here is a sample method reproduce it

lizj at suika x86-64-yocto-1.3]$ source toolchain-1.3-tcmode-default/environment-setup-x86_64-poky-linux
[lizj at suika x86-64-yocto-1.3]$ echo $CC
x86_64-poky-linux-gcc -m64 --sysroot=/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-poky-linux
[lizj at suika x86-64-yocto-1.3]$ $LD --version
GNU ld (GNU Binutils) 2.23.1.20121113
[lizj at suika x86-64-yocto-1.3]$ mkdir -p fake_rootfs/usr/lib
[lizj at suika x86-64-yocto-1.3]$ cp /yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-poky-linux/usr/lib/libc.so fake_rootfs/usr/lib/
[lizj at suika x86-64-yocto-1.3]$ ls fake_rootfs/usr/lib/
libc.so
[lizj at suika x86-64-yocto-1.3]$ $CC -o test test.c -L ./fake_rootfs/usr/lib/
test.c: In function 'main':
test.c:3:9: warning: incompatible implicit declaration of built-in function 'printf' [enabled by default]
/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-pokysdk-linux/usr/bin/x86_64-poky-linux/../../libexec/x86_64-poky-linux/gcc/x86_64-poky-linux/4.7.2/ld: skipping incompatible /lib/libc.so.6 when searching for /lib/libc.so.6
/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-pokysdk-linux/usr/bin/x86_64-poky-linux/../../libexec/x86_64-poky-linux/gcc/x86_64-poky-linux/4.7.2/ld: cannot find /lib/libc.so.6
/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-pokysdk-linux/usr/bin/x86_64-poky-linux/../../libexec/x86_64-poky-linux/gcc/x86_64-poky-linux/4.7.2/ld: skipping incompatible /usr/lib/libc_nonshared.a when searching for /usr/lib/libc_nonshared.a
/yocto/fnst/lizj/build_yocto/x86-64-yocto-1.3/toolchain-1.3-tcmode-default/sysroots/x86_64-pokysdk-linux/usr/bin/x86_64-poky-linux/../../libexec/x86_64-poky-linux/gcc/x86_64-poky-linux/4.7.2/ld: cannot find /usr/lib/libc_nonshared.a
collect2: error: ld returned 1 exit status
-------------------------------------------------------------------------

It seems that ld don‘t  really reasonable to do like that，which binutils-2.22 can handle correctly
Does poky mind this behavior


以上

-- 
Best regards.
Li Zhijian



at 2013-9-20 19:00, Laurentiu Palcu wrote:
> Hi,
>
> On Fri, Sep 20, 2013 at 06:25:19PM +0800, Li Zhijian wrote:
>>>>>>> III） compile a simple C program
>>>>>>> # cat test.c
>>>>>>> int main ()
>>>>>>> {
>>>>>>> printf("hello world\n");
>>>>>>> return 0;
>>>>>>> }
>>>>>>> # source toolchain-1.3-tcmode-default/environment-setup-x86_64-poky-linux
>>>>>>> # $CC -o test test.c -L tmp/sysroots/qemux86-64/usr/lib/ -lm
> OK, it looks like something strange happens in your setup.
>
> To debug it, let's add '-Wl,--verbose' at the end of your command and you
> should be able to see where the linker is looking for libraries. Also,
> the linker script will be printed.
>
> You should see it try your directory first
> tmp/sysroots/qemux86-64/usr/lib/, and then fall through the default ones
> with the sysroot prefix added and, at the end, the system ones:
> /lib:/usr/lib.
>
> Thanks,
> Laurentiu
>
>