[libcamera-devel] [PATCH] README: Add 'ldconfig' note

[Laurent Pinchart]

Hi Kieran,

On Sun, Sep 17, 2023 at 02:50:19PM +0100, Kieran Bingham wrote:
> Quoting Laurent Pinchart (2023-05-24 15:33:43)
> > On Wed, May 24, 2023 at 03:16:42PM +0100, Kieran Bingham wrote:
> > > Quoting Laurent Pinchart (2023-05-24 14:03:24)
> > > > On Wed, May 24, 2023 at 02:50:53PM +0200, Jacopo Mondi via libcamera-devel wrote:
> > > > > On Tue, May 23, 2023 at 12:25:30PM +0100, Kieran Bingham via libcamera-devel wrote:
> > > > > > Provide an update in the README.rst to reflect that a first install may
> > > > > > require a manual call to 'ldconfig' as the root user.
> > > > > >
> > > > > > Meson install does not do this.
> > > > > 
> > > > > Nothing specific about libcamera here, but I guess it doesn't hurt
> > > > > 
> > > > > Reviewed-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> > > > > 
> > > > > > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > > > > > ---
> > > > > >  README.rst | 18 ++++++++++++++++++
> > > > > >  1 file changed, 18 insertions(+)
> > > > > >
> > > > > > diff --git a/README.rst b/README.rst
> > > > > > index 34b6b49f3575..48629280a936 100644
> > > > > > --- a/README.rst
> > > > > > +++ b/README.rst
> > > > > > @@ -37,6 +37,24 @@ To fetch the sources, build and install:
> > > > > >    meson setup build
> > > > > >    ninja -C build install
> > > > > >
> > > > > > +
> > > > > > +First run
> > > > > > +~~~~~~~~~
> > > > > > +
> > > > > > +For a first install, or an install with a newer library version the linker
> > > > > > +configuration may need to be updated. If you experience any error such as :
> > > > 
> > > > Extra space before colon.
> > > > 
> > > > > > +
> > > > > > +::
> > > > > > +
> > > > > > +   cam: error while loading shared libraries: libcamera.so.0.0.4: cannot open shared object file: No such file or directory
> > > > > > +
> > > > > > +please run:
> > > > > > +
> > > > > > +::
> > > > > > +
> > > > > > +  sudo ldconfig
> > > > 
> > > > As Jacopo said, this isn't specific to libcamera, but I suppose it
> > > > doesn't hurt. I hope the next step won't be to document how to add a
> > > > custom directory to /etc/ld.so.conf, as your README.rst shouldn't become
> > > > a Linux 101 tutorial :-)
> > > 
> > > Sure but then you could say why do we bother documenting how to run
> > > 'meson' and 'ninja' ... It *is* specific to /running/ libcamera.
> > > 
> > > The reason for this is because users are confused [0]. For a while it
> > > was required, then meson handled it ... now it doesn't anymore.
> > > 
> > > I'd put a:
> > > 
> > > Suggested-by: Brad Morgan <>
> > > 
> > > But I don't have a full address
> > > 
> > > [0] https://github.com/kbingham/libcamera/issues/70
> > 
> > Maybe we'll need a FAQ at some point to answer miscellaneous questions,
> > to ensure the README.rst won't grow out of control.
> 
> I interpret your lack of positivity in this review as a nack.
> 
> But as you've seen - this is turning into a frequently asked question.

I assume you're referring to
https://bugs.libcamera.org/show_bug.cgi?id=200. The latest comment in
that bug report indicates that ldconfig didn't help.

> We have an FAQ on libcamera.org - but I don't think this is an
> appropriate place for that. The issue occurs when following the
> instructions we provide for installation from source.
> 
> I believe it would be better to fully document all the steps required to
> be able to install /and use/ from source. (i.e. merge this patch)

I'm not opposed to merging this, but you're right that I'm not thrilled
to turn README.rst into a Linux 101 tutorial.

Let's first figure out what the issue in bug #200 is.

> > > > > > +
> > > > > > +
> > > > > >  Dependencies
> > > > > >  ~~~~~~~~~~~~
> > > > > >

-- 
Regards,

Laurent Pinchart