Re: Crossbuild with pkg-config
On Thu, Dec 14, 2023 at 09:46:54PM +0100, IOhannes m zmölnig (Debian/GNU) wrote:
> On 12/14/23 19:51, Randy Pfeifer wrote:
> > Hello,
> > I'm attempting to create and cross-build a package with a simple Makefile using pkg-config to set linking options. I found a solution in theCrossBuildPackagingGuidelines wiki page:
> >
> > In Makefile:
> > include /usr/share/dpkg/buildtools.mk
This is supposed to go into the Debian packaging.
> > PKG_CONFIG?=pkg-config
> > LDLIBS += $(shell $(PKG_CONFIG) --libs <lib...>)
This is supposed to go into the upstream Makefile.
> > This works, but the include makes the upstream package (Makefile) non-portable (debian specific). Is there a better way to accomplish this ?
>
>
> i see two ways:
> 1. just patch the makefile for Debian packaging (it's a bit unclear whether
> your context is actually Debian packaging, but since you quote
> CrossBuildPackagingGuidelines, I assume it is)
Don't. You can never upstream your patch and there is no need for a
patch, because:
> 2. just pass the PKG_CONFIG manually when invoking 'make'. use the power of
> /usr/share/dpkg/buildtools.mk from within your meta-buildsystem (e.g.
> d/rules) and call the actual build with 'make PKG_CONFIG=$(PKG_CONFIG)' or
> similar.
This sounds cumbersome, but this is the way to do it. The contract for
simple Makefiles is that upstreams pick defaults for CC, PKG_CONFIG and
friends but a user may set them. In particular, cross building requires
setting all of them.
Did you know that dh_auto_build automatically sets these (including
PKG_CONFIG) when performing a cross build? As soon as your upstream
Makefile always invokes pkg-config as $(PKG_CONFIG), it'll automatically
just work with dh_auto_build.
Also note that this approach also automatically just works with
buildroot, ptxdist and yocto. :)
Would either of you extend the wiki page?
> 3. (as upstream) do an *optional* include if the buildtools.mk:
>
> ```
> -include /usr/share/dpkg/buildtools.mk
> PKG_CONFIG?=pkg-config
> ```
Don't. This is Debian packaging infrastructure and has no business in
upstream build systems.
Helmut
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