[Buildroot] Failed to load libmmal.so from rpi-userland package via buildroot toolchain on raspberry pi 4

[iman ahmadvand]

Hi, peter.

Sorry for the outdated reply!
I just mean both cases, dlopeb() and ldd examine on libmmal.so succeed by
changing to glibc (and also VLC codec plugin) as you suggested.
But don't know what happens with uclibc! which break rpi-userland MMAL
components register

Regards.
Iman.

On Sat, Mar 28, 2020 at 7:04 PM Peter Seiderer <ps.report at gmx.net> wrote:

> Hello Iman,
>
> On Sat, 28 Mar 2020 17:14:59 +0430, iman ahmadvand <iman72411 at gmail.com>
> wrote:
>
> > Hi Peter.
> >
> > Exact same situation for me when changing to glibc or using external
> linaro
> > toolchain(which comes with glibc).
>
> What do you mean by 'exact same situation', the simple dlopen() test, or
> the
> complete VLC test? Did you do a *complete* re-build and complete
> installation?
> Can you show the output from 'ldd /usr/lib/libmmal.so'?
>
> Regards,
> Peter
>
> > Don't know what's going on.
> > Interesting thread: https://github.com/raspberrypi/userland/issues/178
> >
> > Regards.
> > IMAN.
> >
> > On Sat, Mar 28, 2020 at 3:01 PM Peter Seiderer <ps.report at gmx.net>
> wrote:
> >
> > > Hello Iman,
> > >
> > > On Sat, 28 Mar 2020 11:39:46 +0430, iman ahmadvand <
> iman72411 at gmail.com>
> > > wrote:
> > >
> > > > Hi everyone.
> > > > It seems that loading the MMAL interface shared libraries from
> > > rpi-userland
> > > > package via simple dlopen is not possible, or more specific, the
> packages
> > > > or binaries such as VLC or VLC codec plugin (libavcodec_plugin)
> could not
> > > > load the libavcodec from FFmpeg which in turn depends on libmmal*.so
> > > >
> > > > The steps to reproduce(with BR2_PACKAGE_RPI_USERLAND enabled,
> > > > BR2_STRIP_strip disabled, BR2_OPTIMIZE_0 enabled):
> > > > git clone git://git.busybox.net/buildroot buildroot && cd buildroot
> &&
> > > git
> > > > checkout 2019.11.01
> > > > make raspberrypi4_defconfig && make all
> > > >
> > > > Then in this image try to run a simple c routine with dlopen(), if
> you do
> > > > so, for example, ./dltest /usr/lib/libmmal.so you will end up with:
> > > >
> > > > symbol 'mmal_port_payload_alloc': can't resolve symbol
> > > > symbol 'mmal_port_payload_free': can't resolve symbol
> > > > symbol 'mmal_port_log_category': can't resolve symbol
> > > >
> > >
> > > Can confirm your failure...did not (yet) find out what fails exactly,
> but
> > > ldd produces the following ouput (mind the 0x00000000):
> > >
> > >         $ ldd /usr/lib/libmmal.so
> > > checking sub-depends for '/usr/lib/libmmal_vc_client.so'
> > > checking sub-depends for '/usr/lib/libmmal_components.so'
> > > checking sub-depends for '/usr/lib/libvchiq_arm.so'
> > > checking sub-depends for '/usr/lib/libvcsm.so'
> > > checking sub-depends for '/usr/lib/libmmal_core.so'
> > > checking sub-depends for '/usr/lib/libmmal_util.so'
> > > checking sub-depends for '/usr/lib/libcontainers.so'
> > > checking sub-depends for '/usr/lib/libvcos.so'
> > > checking sub-depends for '/lib/libc.so.0'
> > >         ld-uClibc.so.1 => /lib/ld-uClibc.so.1 (0xb6f8b000)
> > >         libmmal_vc_client.so => /usr/lib/libmmal_vc_client.so
> (0x00000000)
> > >         libmmal_components.so => /usr/lib/libmmal_components.so
> > > (0x00000000)
> > >         libvchiq_arm.so => /usr/lib/libvchiq_arm.so (0x00000000)
> > >         libvcsm.so => /usr/lib/libvcsm.so (0x00000000)
> > >         libmmal_core.so => /usr/lib/libmmal_core.so (0x00000000)
> > >         libmmal_util.so => /usr/lib/libmmal_util.so (0x00000000)
> > >         libcontainers.so => /usr/lib/libcontainers.so (0x00000000)
> > >         libvcos.so => /usr/lib/libvcos.so (0x00000000)
> > >         libc.so.0 => /lib/libc.so.0 (0x00000000)
> > >         /lib/ld-uClibc.so.1 => /lib/ld-uClibc.so.1 (0x00000000)
> > >
> > >
> > > After changing the buildroot toolchain from uclibc to glibc (and a full
> > > re-build) dlopen() of /usr/lib/libmmal.so works and ldd produces the
> > > following output:
> > >
> > >         $ ldd /usr/lib/libmmal.so
> > >         linux-vdso.so.1 (0xbea59000)
> > >         libmmal_vc_client.so => /usr/lib/libmmal_vc_client.so
> (0xb6f5f000)
> > >         libmmal_components.so => /usr/lib/libmmal_components.so
> > > (0xb6f44000)
> > >         libvchiq_arm.so => /usr/lib/libvchiq_arm.so (0xb6f2e000)
> > >         libvcsm.so => /usr/lib/libvcsm.so (0xb6f14000)
> > >         libmmal_core.so => /usr/lib/libmmal_core.so (0xb6ef6000)
> > >         libmmal_util.so => /usr/lib/libmmal_util.so (0xb6ed8000)
> > >         libcontainers.so => /usr/lib/libcontainers.so (0xb6eb5000)
> > >         libvcos.so => /usr/lib/libvcos.so (0xb6e9c000)
> > >         libpthread.so.0 => /lib/libpthread.so.0 (0xb6e71000)
> > >         libdl.so.2 => /lib/libdl.so.2 (0xb6e5e000)
> > >         librt.so.1 => /lib/librt.so.1 (0xb6e47000)
> > >         libc.so.6 => /lib/libc.so.6 (0xb6cfb000)
> > >         /lib/ld-linux-armhf.so.3 (0xb6f8f000)
> > >
> > > Regards,
> > > Peter
> > >
> > >
> > > > Or for another proof of the issue, you can run VLC with X11 to play
> an
> > > > MPEG-4 video, and you will  end up with VLC could not load the codec
> > > module
> > > > because of the same thing:
> > > >
> > > > main debug: loading plugins cache file
> /usr/lib/vlc/plugins/plugins.dat
> > > > main warning: cannot read /usr/lib/vlc/plugins/plugins.dat: No such
> > > > file or directory
> > > > main debug: recursively browsing `/usr/lib/vlc/plugins'
> > > > main warning: cannot load module
> > > > `/usr/lib/vlc/plugins/codec/libavcodec_plugin.so' ((null)
> > > >
> > > > Any idea about this?
> > > >
> > > > Best Regards.
> > > > IMAN.
> > >
> > >
>
>
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