Re: [EXT] Re: [PATCH 1/1] build: update link args and includes for libarchive

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Oct 23, 2023 at 12:46:59PM +0000, Srikanth Yalavarthi wrote:
> > -----Original Message-----
> > From: Bruce Richardson <bruce.richardson@intel.com>
> > Sent: 23 October 2023 17:24
> > To: Srikanth Yalavarthi <syalavarthi@marvell.com>
> > Cc: Aaron Conole <aconole@redhat.com>; Igor Russkikh
> > <irusskikh@marvell.com>; David Marchand <david.marchand@redhat.com>;
> > dev@dpdk.org; Shivah Shankar Shankar Narayan Rao
> > <sshankarnara@marvell.com>; Jerin Jacob Kollanukkaran
> > <jerinj@marvell.com>; stable@dpdk.org
> > Subject: Re: [EXT] Re: [PATCH 1/1] build: update link args and includes for
> > libarchive
> > 
> > On Mon, Oct 23, 2023 at 11:40:14AM +0000, Srikanth Yalavarthi wrote:
> > > > -----Original Message-----
> > > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > > Sent: 23 October 2023 14:56
> > > > To: Srikanth Yalavarthi <syalavarthi@marvell.com>
> > > > Cc: Aaron Conole <aconole@redhat.com>; Igor Russkikh
> > > > <irusskikh@marvell.com>; David Marchand
> > <david.marchand@redhat.com>;
> > > > dev@dpdk.org; Shivah Shankar Shankar Narayan Rao
> > > > <sshankarnara@marvell.com>; Jerin Jacob Kollanukkaran
> > > > <jerinj@marvell.com>; stable@dpdk.org
> > > > Subject: [EXT] Re: [PATCH 1/1] build: update link args and includes
> > > > for libarchive
> > > >
> > > > External Email
> > > >
> > > > --------------------------------------------------------------------
> > > > -- On Fri, Oct 20, 2023 at 10:01:35AM -0700, Srikanth Yalavarthi
> > > > wrote:
> > > > > In order to avoid linking with all libraries listed as
> > > > > Libs.private in libarchive.pc, libarchive is not added to ext_deps during
> > meson setup.
> > > > >
> > > > > Since libarchive is not added to ext_deps, cross-compilation or
> > > > > native compilation with libarchive installed in non-standard
> > > > > location fails with errors related to "cannot find -larchive"
> > > > > or "archive.h: No such file or directory". In order to fix the
> > > > > build failures, user is required to define the 'c_args' and 'c_link_args'
> > > > > with '-I<includedir>' and '-L<libdir>'.
> > > > >
> > > > > This patch updates meson build files to add libarchive's
> > > > > includedir and libdir to compiler flags and would not require
> > > > > setting c_args and c_link_args externally.
> > > > >
> > > > > Fixes: 40edb9c0d36b ("eal: handle compressed firmware")
> > > > > Cc: stable@dpdk.org
> > > > >
> > > > > Signed-off-by: Srikanth Yalavarthi <syalavarthi@marvell.com>
> > > > > ---
> > > >
> > > > Checking back through the mail archives I'm still a little unclear
> > > > as to what breaks when we try using libarchive as any other package
> > > > with a pkg-config file? I would have thought the best solution was
> > > > just to add libarchive as an external dependency, found using
> > > > pkg-config, to EAL. When we add it as a dependency, rather than
> > > > using c/ldflags, we should get all this path fixup for free?
> > > > Can you clarify what breaks when we add libarchive as a libeal
> > > > dependency only?
> > >
> > > Below is my observation.
> > >
> > > In current implementation, we are looking for libarchive's availability
> > through pkg-config.
> > > When found, we are setting RTE_HAS_LIBARCHIVE=1 and adding '-larchive'
> > to ldflags.
> > >
> > > Since, we are not adding libarchive to ext_deps (to avoid linking with
> > > deps.private), the
> > 
> > This is the bit I'm a bit stuck on. What is the issues with adding libarchive to
> > ext_deps? For other libs, when doing static builds we have to link with
> > deps.private and it's the correct behaviour AFAIK. Not doing so would surely
> > lead to problematic builds, no?
> 
> I agree on adding to ext_deps as it's the correct behaviour.
> 
> However, there was a discussion in mail archives regarding this.
> https://inbox.dpdk.org/dev/20210605004024.660267a1@sovereign/
> 
> Adding Dmitry Kozlyuk for comments.
> 
Testing it out myself, the sample applications don't build statically due
to missing dependencies. The libarchive-dev package on Ubuntu, doesn't seem
to install all dependent packages for static builds.
I had to manually install liblz4-dev and libacl1-dev packages, and then
test-meson-builds ran successfully.

Personally, it looks to me like a packaging issue, in that I would expect
the -dev package to install all required dependent dev packages. I also
think using the pkgconfig as a regular dependency is the way we should look
to go, and if necessary, document the list of extra dependencies needed for
libarchive in our docs.

/Bruce