Re: [dpdk-dev] [PATCH] avoid libfdt checks adding full paths to pkg-config

[Christian Ehrhardt <christian.ehrhardt@canonical.com>]

On Wed, Sep 2, 2020 at 1:25 PM Bruce Richardson
<bruce.richardson@intel.com> wrote:
>
> On Wed, Sep 02, 2020 at 01:10:30PM +0200, Christian Ehrhardt wrote:
> > The checks for libfdt try dependency() first which would only work if
> > a pkg-config would be present but libfdt has none.
> > Then it probes for the lib path itself via cc.find_library.
> >
> > But later it adds the result of either probe to ext_deps which ends up
> > in build and also the resulting pkg-config to contain toolchain versioned
> > paths in Libs.private like:
> >   /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/libfdt.so
> > which obviously breaks on toolchain updates.
> >
> > In general libs used multiple times - ipn3ke + ifpga in this case - are
> > checked centrally in config/meson.build so move it there and fix the
> > adding of dependencies to not use the full file path.
> >
> > The result is libfdt in pkg-config now showing up as:
> >   Libs.private: -pthread -lm -ldl -lnuma -lfdt -lpcap
> >
> > Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
> > Reviewed-by: Luca Boccassi <bluca@debian.org>
> > ---
> >  config/meson.build             | 9 +++++++++
> >  drivers/net/ipn3ke/meson.build | 6 +-----
> >  drivers/raw/ifpga/meson.build  | 7 +------
> >  3 files changed, 11 insertions(+), 11 deletions(-)
> >
> > diff --git a/config/meson.build b/config/meson.build
> > index cff8b33dd2..1c8317e750 100644
> > --- a/config/meson.build
> > +++ b/config/meson.build
> > @@ -150,6 +150,15 @@ if numa_dep.found() and cc.has_header('numaif.h')
> >       dpdk_extra_ldflags += '-lnuma'
> >  endif
> >
> > +has_libfdt = 0
> > +fdt_dep = cc.find_library('libfdt', required: false)
> > +if fdt_dep.found() and cc.has_header('fdt.h')
> > +     dpdk_conf.set10('RTE_HAS_LIBFDT', true)
> > +     has_libfdt = 1
> > +     add_project_link_arguments('-lfdt', language: 'c')
> > +     dpdk_extra_ldflags += '-lfdt'
> > +endif
> > +
> >  # check for libbsd
> >  libbsd = dependency('libbsd', required: false)
> >  if libbsd.found()
> > diff --git a/drivers/net/ipn3ke/meson.build b/drivers/net/ipn3ke/meson.build
> > index ec9cb7daf0..d5000d807c 100644
> > --- a/drivers/net/ipn3ke/meson.build
> > +++ b/drivers/net/ipn3ke/meson.build
> > @@ -9,11 +9,7 @@
> >  #  rte_eth_switch_domain_free()
> >  #
> >
> > -dep = dependency('libfdt', required: false)
> > -if not dep.found()
> > -     dep = cc.find_library('libfdt', required: false)
> > -endif
> > -if not dep.found()
> > +if has_libfdt == 0
>
> Minor nit, for readability, I'd suggest using "not has_libfdt", but what is
> here can work too.

Thanks, improved according to your suggestion, v2 submission inbound.

> >       build = false
> >       reason = 'missing dependency, "libfdt"'
> >       subdir_done()
> > diff --git a/drivers/raw/ifpga/meson.build b/drivers/raw/ifpga/meson.build
> > index 05a1711b5d..da454b1942 100644
> > --- a/drivers/raw/ifpga/meson.build
> > +++ b/drivers/raw/ifpga/meson.build
> > @@ -1,11 +1,7 @@
> >  # SPDX-License-Identifier: BSD-3-Clause
> >  # Copyright(c) 2018 Intel Corporation
> >
> > -dep = dependency('libfdt', required: false)
> > -if not dep.found()
> > -     dep = cc.find_library('libfdt', required: false)
> > -endif
> > -if not dep.found()
> > +if has_libfdt == 0
> >       build = false
> >       reason = 'missing dependency, "libfdt"'
> >       subdir_done()
> > @@ -16,7 +12,6 @@ objs = [base_objs]
> >
> >  deps += ['ethdev', 'rawdev', 'pci', 'bus_pci', 'kvargs',
> >       'bus_vdev', 'bus_ifpga', 'net', 'pmd_i40e', 'pmd_ipn3ke']
> > -ext_deps += dep
> >
> >  sources = files('ifpga_rawdev.c')
> >
> > --
> Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>



-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd