Alan Feuerbacher wrote:
In building various optional packages in BLFS, I've found that certain packages may or may not automatically install the options, including non-BLFS options; hence my question about the meaning of "default auto" in configure scripts.For example, in BLFS systemd version 8.0, I'm looking at "configure --help" for vlc-2.2.4. It contains many -- flags like --enable-ogg or --disable-mpc, many of which have a comment like "(do not) use libmpcdec (default auto)". The BLFS book calls out many of these flagged packages as optional dependencies, so I would have thought that if you did not install an optional package, a BLFS package like VLC would not use it. For example, configuring VLC with --enable-mpc would use Musepack *IF* you already had Musepack installed. Conversely, I would think that --disable-mpc would not use either your installed version, or a version internal to VLC. But down in the source code is a pile of code that installs every one of the options as if it were an external version. The code automatically downloads a package, applies patches, compiles and installs it. For example, /sources/vlc-2.2.4/contrib/src contains a bunch of directories that contain a rules.mak and patch files. I'm not yet savvy enough to figure out from the code whether these are all installed automatically or not if you don't give configure an --enable flag. What I _can_ say is that after installing VLC without most of the options, the options that were not installed by me were not installed by VLC in the standard places, such as binaries for "mpc" ("Musepack") being installed in /usr/bin or include files for "mpc" being installed in /usr/include. So, given the above, what exactly does "default auto" mean?
It's not absolute, but generally it means configure will look for it and use what it finds. It will not (generally) complain if the package is not installed.
For these options, if the package is found, you have to explicitly disable it in configure if you do not want it built into the package.
-- Bruce -- http://lists.linuxfromscratch.org/listinfo/blfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
