Em Tue, 27 Sep 2016 00:40:51 +0300 Sakari Ailus <sakari.ailus@xxxxxx> escreveu: > Hi Mauro, > > On Mon, Sep 26, 2016 at 01:59:45PM -0300, Mauro Carvalho Chehab wrote: > > Em Mon, 26 Sep 2016 18:46:40 +0300 > > Sakari Ailus <sakari.ailus@xxxxxx> escreveu: > > > > > Hi Mauro, > > > > > > On Mon, Sep 19, 2016 at 11:19:12AM -0300, Mauro Carvalho Chehab wrote: > > > > Em Mon, 19 Sep 2016 16:21:30 +0300 > > > > Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> escreveu: > > > > > > > > > Hi Mauro, > > > > > > > > > > On 09/19/16 14:22, Mauro Carvalho Chehab wrote: > > > > > > Em Mon, 19 Sep 2016 13:50:25 +0300 > > > > > > Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> escreveu: > > > > > > > > > > > >> v4l2-compliance and v4l2-ctl depend on librt and libpthread. The symbols > > > > > >> are found by the linker only if these libraries are specified after the > > > > > >> objects that depend on them. > > > > > >> > > > > > >> As LDFLAGS variable end up expanded on libtool command line before LDADD, > > > > > >> move the libraries to LDADD after local objects. -lpthread is added as on > > > > > >> some systems librt depends on libpthread. This is the case on Ubuntu 16.04 > > > > > >> for instance. > > > > > >> > > > > > >> After this patch, creating a static build using the command > > > > > >> > > > > > >> LDFLAGS="--static -static" ./configure --disable-shared --enable-static > > > > > > > > > > > > It sounds weird to use LDFLAGS="--static -static" here, as the > > > > > > configure options are already asking for static. > > > > > > > > > > > > IMHO, the right way would be to change configure.ac to add those LDFLAGS > > > > > > when --disable-shared is used. > > > > > > > > > > That's one option, but then shared libraries won't be built at all. > > > > > > > > Well, my understanding is that --disable-shared is meant to disable > > > > building the shared library build :) > > > > > > > > > I'm > > > > > not sure what would be the use cases for that, though: static linking > > > > > isn't very commonly needed except when you need to run the binaries > > > > > elsewhere (for whatever reason) where you don't have the libraries you > > > > > linked against available. > > > > > > > > Yeah, that's the common usage. It is also interesting if someone > > > > wants to build 2 versions of the same utility, each using a > > > > different library, for testing purposes. > > > > > > > > The usecase I can't see is to use --disable-shared but keeping > > > > using the dynamic library for the exec files. > > > > > > There are three primary options here, > > > > > > 1. build an entirely static binary, > > > 2. build a binary that relies on dynamic libraries as well and > > > 3. build a binary that relies on dynamic libraries outside v4l-utils package > > > but that links v4l-utils originating libraries statically. > > > > > > If you say 3. is not needed then we could just use --disable-shared also to > > > tell that static binaries are to be built. > > > > > > 3. is always used for libv4l2subdev and libmediactl as the libraries do not > > > have stable APIs. > > > > Sakari, > > > > I can't see what you mean by scenario (2). I mean, if > > --disable-shared is called, it *should not* use dynamic libraries > > for any library provided by v4l-utils, as the generated binaries will > > either: > > > > a) don't work, because those libraries weren't built; > > b) will do the wrong thing, as they'll be dynamically linked > > to an older version of the library. > > > > So, there are only 3 possible scenarios, IMHO: > > > > 1) dynamic libraries, dynamic execs > > 2) static v4l-utils libraries, static execs > > 3) static v4l-utils libraries, static links for v4l-utils libs, dyn for the rest. > > > > In practice, I don't see any reason for keeping support for both (2) > > and (3), as all usecases for (3) can be covered by a fully static > > exec. It is also very confusing for one to understand that. > > For example, right now, we have those static/shared options: > > > > --enable-static[=PKGS] build static libraries [default=yes] > > --enable-shared[=PKGS] build shared libraries [default=yes] > > > > with, IMHO, sounds confusing, as those options don't seem to be > > orthogonal. I mean, what happens someone calls ./configure with: > > > > ./configure --disable-static --disable-shared > > That doesn't make much sense --- to disable the build for both static and > dynamic libraries. Yes, but it is still a "valid" set of options, as configure won't complain. Yet, this will cause build errors: /usr/bin/ld: ../../lib/libdvbv5/.libs/libdvbv5.a(libdvbv5_la-dvb-dev-local.o): undefined reference to symbol 'pthread_cancel@@GLIBC_2.2.5' /usr/lib64/libpthread.so.0: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status > What would you prefer? Link binaries statically iff shared libraries are not > built? I'd just like to get this fixed. Currently building static binaries > is simply broken. IMHO, if --disable-shared is issued, it should do static linking for all libraries. Gregor may have a different opinion, as I think he knows a lot more about how distros usually expect those options to be handled. Thanks, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
