[Buildroot] systemd: build failure against pam on arm

[Waldemar Brodkorb <wbx@openadk.org>]

Hi Christian,
Christian Stewart wrote,

> Hi Waldemar, All,
> 
> Christian Stewart <christian@paral.in> writes:
> > Hi Waldemar,
> >
> > Waldemar Brodkorb <wbx@openadk.org> writes:
> >>> There are no extra pam files in my Buildroot tree - before building I
> >>> ensure this with a "git clean -xfd" and I've searched the tree as well.
> >>
> >> But that is strange then.
> >> find . -name libpam_misc.so\*
> >> ./output/build/linux-pam-1.3.0/libpam_misc/.libs/libpam_misc.so.0
> >> ./output/build/linux-pam-1.3.0/libpam_misc/.libs/libpam_misc.so
> >> ./output/build/linux-pam-1.3.0/libpam_misc/.libs/libpam_misc.so.0.82.1
> >
> > ... please note that I am building out of tree. There are no
> > limpam_misc* inside the "buildroot tree" which includes the main source
> > tree. When the compilation fails, inside my "output tree":
> 
> I can confirm now that even in-tree builds result in the same thing:

..

I believe it is an issue how gcc is calling the linker.
In my case I see following:
libsystemd-shared.la -lpam -lpam_misc
-L/home/wbx/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib
-lkmod

So the linker does not get -L before -lpam -lpam_misc pointing to
the sysroot. 

If you start gcc with verbose linker output you see:
./output/host/bin/arm-buildroot-linux-gnueabihf-gcc -Wl,-verbose

The included linker script has:
SEARCH_DIR("=/home/wbx/buildroot/output/host/arm-buildroot-linux-gnueabihf/lib");
SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib");
SEARCH_DIR("=/usr/lib");

In my case on Debian libpam.so is not in the search dirs, but in
ls /lib/x86_64-linux-gnu/libpam.so.0*
/lib/x86_64-linux-gnu/libpam.so.0
/lib/x86_64-linux-gnu/libpam.so.0.83.1
wbx at helium:~/buildroot$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 8.9 (jessie)
Release:        8.9
Codename:       jessie

In you case the linker finds libpam.so in /lib and try to use it.

To verify my analyzation you can add -L<sysrootpathofyourbr> into:
systemd/Makefile
PAM_LIBS =
-L/home/paralin/buildroot/pi3/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib
-lpam -lpam_misc

Like in KMOD_LIBS. Then just continue the build with make V=1 and
see if it succeeds.

As systemd is switching completely to meson buildsystem a
upstreamable patch is not possible.

best regards
 Waldemar