[Slackbuilds-users] Meaning of PKGARCH=$(uname -m)_custom in ffmpeg.SlackBuild

[Erik Hanson]

On Sat, 21 May 2016 17:04:46 +0200
Andrzej Telszewski <atelszewski at gmail.com> wrote:

> On 21/05/16 16:53, Erik Hanson wrote:
> > On Sat, 21 May 2016 12:18:53 +0200
> > Andrzej Telszewski <atelszewski at gmail.com> wrote:
> >  
> >> Hi,
> >>
> >> ffmpeg.SlackBuild sets the package arch to $(uname -m)_custom
> >> Why is that?
> >>
> >> This is somehow in reference to my previous question:
> >> https://lists.slackbuilds.org/pipermail/slackbuilds-users/2016-March/015772.html
> >>
> >> So, can the ffmpeg package built on one machine be safely used on
> >> another machine?  
> >
> > The result is a non-portable package. It's optimized for the CPU
> > it's been compiled with. If you're working in an environment that
> > consists of modern hardware, it's probably not too relevant.
> > Consider it a warning that using a newer/faster machine to build
> > the package and then installing it on an older/slower machine might
> > mean the binary won't run as expected.
> >  
> 
> Thanks. I haven't researched the topic yet and I'm just going to ask 
> here, but feel free not to answer, since the question probably does
> not belong here:
> 
> Is it possible to have ffmpeg being built as any other Slackware
> package is?

I believe so, I seem to remember something (it's been a while, memory
is fuzzy) but you either pass a single parameter, like
"--no-optimizations" or several, such as "--no-sse --nosse2
--no-mmx" ... etc. These flags are examples, you'd need to research,
look at the output of 'configure --help' and determine how to do it.

Knowing the destination hardware, you could tune it. I will say, it
seems obvious that just gutting all the optimizations would give you
an ffmpeg binary that's pointlessly slow. I doubt anyone wants this.


-- 
Erik