[Ffmpeg-devel] [RFC] dlopen vs linking for external libraries

Michael Niedermayer michaelni
Sun Feb 11 22:20:52 CET 2007


On Sun, Feb 11, 2007 at 10:53:46PM +0200, Uoti Urpala wrote:
> On Sun, 2007-02-11 at 20:16 +0000, M?ns Rullg?rd wrote:
> > Uoti Urpala <uoti.urpala at pp1.inet.fi> writes:
> > > present. They don't cause problems with proper binary packaging systems
> > > either (such as Debian) when the system can take care of the
> > > dependencies. The only problem case would be trying to distribute
> > > binaries without proper packaging.
> > 
> > I think Michael was complaining about the endless lists of
> > dependencies that are typical for binary packages.  Most distros tend
> > to enable everything that can possibly be enabled, so you end up with
> > many gigabytes of disk space taken up by stuff you never ever use.
> On this Debian system /usr/lib is less than a gigabyte and the
> whole /usr is about 2.1 GiB. That includes things like OpenOffice.
> Ending up with "many gigabytes" of space taken by unnecessary
> dependencies alone sounds highly exaggerated.

exaggeration does not change the validity of the point, if your system
has only a few megabytes of space, wasting a few hundread megabyte is not
an option

> If the binary distros tried to make features optional and used dlopen()
> or created separate packages with enabled/disabled features the
> increased complexity would make it a net loss (yes they have considered
> that). 

our dlopen code doesnt look that complex ...
and noone here has proposed to add separate packages with enabled/disabled
features ...

> For a program typically used with video files the space savings
> matter even less than for most others.

these statements remind me of http://en.wikipedia.org/wiki/Weasel_words

in the case here, you make 3 claims (dlopen increases complexity so much
that its generally not a worth it), (its generally useless) and (even more
useless for video tools) id like to know who said that? you?
and why should we care what that person said compared to an actual technical
statement which could be verified ...

for example on embeded or old hardware with little available space
you might not want to have 1mb space wasted for 3 external libs and compiling
everthing yourself also has disadvantages, especially on slow hardware with
little space available ... (yeah gcc does need surprising amounts of memory)
so we would end up with cross compilation, is cross compilation done by many
users really less complex then 10 lines of code for dlopen() ? which needs
near 0 maintaince time, just look how many changes the existing dlopen code
needed over time ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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