[PATCH v3] build: select optional libraries

[David Marchand <david.marchand@redhat.com>]

There is currently no way to know which libraries are optional.
Introduce a enable_libs option (close to what we have for drivers) so
that packagers or projects consuming DPDK can more easily select the
optional libraries that matter to them and disable other optional
libraries.

Deprecated libraries are handled via some logic in lib/meson.build
rather than a default value in meson_options.txt.
Enabling deprecated libraries is achieved by requesting all
libraries to be built in the CI.

kni dependency to IOVA configuration is moved to its own meson.build.

Note: the enabled_libs variable is renamed for sake of consistency wrt to
drivers and applications similar variables.

Signed-off-by: David Marchand <david.marchand@redhat.com>
---
The topic was raised again while Stephen was reviewing stale patches in
patchwork. The idea of this patch is the same as before.
I simply rebased the change (and dealt with the deprecated libraries that
added some little complication).

Changes since v2:
- moved the IOVA check for kni build in lib/kni/meson.build,
- reworked deprecated libraries handling by only considering them when
  no enable_libs option is set. With this, no need for a default value
  in meson_options.txt, yet configurations in the CI must be adjusted,
- moved mandatory libraries check after enable/disable_libs evaluation,

---
 .ci/linux-build.sh             |  2 +-
 app/test/meson.build           |  2 +-
 buildtools/chkincs/meson.build |  2 +-
 devtools/test-meson-builds.sh  |  4 ++--
 lib/kni/meson.build            |  5 ++++
 lib/meson.build                | 44 ++++++++++++++++++++--------------
 meson.build                    |  3 ++-
 meson_options.txt              |  4 +++-
 8 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/.ci/linux-build.sh b/.ci/linux-build.sh
index 9631e342b5..a4e474a900 100755
--- a/.ci/linux-build.sh
+++ b/.ci/linux-build.sh
@@ -97,7 +97,7 @@ if [ "$MINI" = "true" ]; then
     OPTS="$OPTS -Denable_drivers=net/null"
     OPTS="$OPTS -Ddisable_libs=*"
 else
-    OPTS="$OPTS -Ddisable_libs="
+    OPTS="$OPTS -Denable_libs=*"
 fi
 
 if [ "$ASAN" = "true" ]; then
diff --git a/app/test/meson.build b/app/test/meson.build
index d0fabcbb8b..f3217ae577 100644
--- a/app/test/meson.build
+++ b/app/test/meson.build
@@ -152,7 +152,7 @@ test_sources = files(
         'virtual_pmd.c',
 )
 
-test_deps = enabled_libs
+test_deps = dpdk_libs_enabled
 # as well as libs, the pci and vdev bus drivers are needed for a lot of tests
 test_deps += ['bus_pci', 'bus_vdev']
 
diff --git a/buildtools/chkincs/meson.build b/buildtools/chkincs/meson.build
index 378c2f19ef..f2dadcae18 100644
--- a/buildtools/chkincs/meson.build
+++ b/buildtools/chkincs/meson.build
@@ -22,7 +22,7 @@ sources += gen_c_files.process(dpdk_chkinc_headers)
 # so we always include them in deps list
 deps = [get_variable('shared_rte_bus_vdev'), get_variable('shared_rte_bus_pci')]
 # add the rest of the libs to the dependencies
-foreach l:enabled_libs
+foreach l:dpdk_libs_enabled
     deps += get_variable('shared_rte_' + l)
 endforeach
 
diff --git a/devtools/test-meson-builds.sh b/devtools/test-meson-builds.sh
index 9131088c9d..4f93702e1f 100755
--- a/devtools/test-meson-builds.sh
+++ b/devtools/test-meson-builds.sh
@@ -122,8 +122,8 @@ config () # <dir> <builddir> <meson options>
 	options=
 	# deprecated libs may be disabled by default, so for complete builds ensure
 	# no libs are disabled
-	if ! echo $* | grep -q -- 'disable_libs' ; then
-		options="$options -Ddisable_libs="
+	if ! echo $* | grep -q -- 'enable_libs' ; then
+		options="$options -Denable_libs=*"
 	fi
 	if echo $* | grep -qw -- '--default-library=shared' ; then
 		options="$options -Dexamples=all"
diff --git a/lib/kni/meson.build b/lib/kni/meson.build
index 8a71d8ba6f..5ce410f7f2 100644
--- a/lib/kni/meson.build
+++ b/lib/kni/meson.build
@@ -7,6 +7,11 @@ if is_windows
     subdir_done()
 endif
 
+if dpdk_conf.get('RTE_IOVA_IN_MBUF') == 0
+    build = false
+    reason = 'requires IOVA in mbuf (set enable_iova_as_pa option)'
+endif
+
 if not is_linux or not dpdk_conf.get('RTE_ARCH_64')
     build = false
     reason = 'only supported on 64-bit Linux'
diff --git a/lib/meson.build b/lib/meson.build
index 9677239236..6018f5230d 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -92,20 +92,18 @@ dpdk_libs_deprecated += [
         'kni',
 ]
 
-disabled_libs = []
-opt_disabled_libs = run_command(list_dir_globs, get_option('disable_libs'),
+disable_libs = run_command(list_dir_globs, get_option('disable_libs'),
         check: true).stdout().split()
-if dpdk_conf.get('RTE_IOVA_IN_MBUF') == 0
-    opt_disabled_libs += ['kni']
+enable_libs = run_command(list_dir_globs, get_option('enable_libs'),
+        check: true).stdout().split()
+if enable_libs.length() == 0
+    enable_libs = []
+    foreach l:run_command(list_dir_globs, '*', check: true).stdout().split()
+        if l not in dpdk_libs_deprecated
+            enable_libs += [l]
+        endif
+    endforeach
 endif
-foreach l:opt_disabled_libs
-    if not optional_libs.contains(l)
-        warning('Cannot disable mandatory library "@0@"'.format(l))
-        continue
-    endif
-    disabled_libs += l
-endforeach
-
 
 default_cflags = machine_args
 default_cflags += ['-DALLOW_EXPERIMENTAL_API']
@@ -115,8 +113,6 @@ if cc.has_argument('-Wno-format-truncation')
     default_cflags += '-Wno-format-truncation'
 endif
 
-enabled_libs = [] # used to print summary at the end
-
 foreach l:libraries
     build = true
     reason = '<unknown reason>' # set if build == false to explain why
@@ -141,13 +137,25 @@ foreach l:libraries
         deps += ['eal']
     endif
 
-    if disabled_libs.contains(l)
+    if not enable_libs.contains(l)
+        build = false
+        reason = 'not in enabled libraries build config'
+    elif disable_libs.contains(l)
         build = false
         reason = 'explicitly disabled via build config'
-        if dpdk_libs_deprecated.contains(l)
+    endif
+
+    if not build
+        if not optional_libs.contains(l)
+            warning('Cannot disable mandatory library "@0@"'.format(l))
+            build = true
+            reason = '<unknown reason>'
+        elif dpdk_libs_deprecated.contains(l)
             reason += ' (deprecated lib)'
         endif
-    else
+    endif
+
+    if build
         if dpdk_libs_deprecated.contains(l)
             warning('Enabling deprecated library, "@0@"'.format(l))
         endif
@@ -183,7 +191,7 @@ foreach l:libraries
         continue
     endif
 
-    enabled_libs += name
+    dpdk_libs_enabled += name
     dpdk_conf.set('RTE_LIB_' + name.to_upper(), 1)
     install_headers(headers)
     install_headers(indirect_headers)
diff --git a/meson.build b/meson.build
index 992ca91e88..39cb73846d 100644
--- a/meson.build
+++ b/meson.build
@@ -44,6 +44,7 @@ dpdk_extra_ldflags = []
 dpdk_libs_deprecated = []
 dpdk_apps_disabled = []
 dpdk_libs_disabled = []
+dpdk_libs_enabled = []
 dpdk_drvs_disabled = []
 testpmd_drivers_sources = []
 testpmd_drivers_deps = []
@@ -134,7 +135,7 @@ message(output_message + '\n')
 output_message = '\n=================\nLibraries Enabled\n=================\n'
 output_message += '\nlibs:\n\t'
 output_count = 0
-foreach lib:enabled_libs
+foreach lib:dpdk_libs_enabled
     output_message += lib + ', '
     output_count += 1
     if output_count == 8
diff --git a/meson_options.txt b/meson_options.txt
index 82c8297065..af54f8b8d4 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -10,7 +10,7 @@ option('disable_apps', type: 'string', value: '', description:
        'Comma-separated list of apps to explicitly disable.')
 option('disable_drivers', type: 'string', value: '', description:
        'Comma-separated list of drivers to explicitly disable.')
-option('disable_libs', type: 'string', value: 'flow_classify,kni', description:
+option('disable_libs', type: 'string', value: '', description:
        'Comma-separated list of libraries to explicitly disable. [NOTE: not all libs can be disabled]')
 option('drivers_install_subdir', type: 'string', value: 'dpdk/pmds-<VERSION>', description:
        'Subdirectory of libdir where to install PMDs. Defaults to using a versioned subdirectory.')
@@ -20,6 +20,8 @@ option('enable_apps', type: 'string', value: '', description:
        'Comma-separated list of apps to build. If unspecified, build all apps.')
 option('enable_drivers', type: 'string', value: '', description:
        'Comma-separated list of drivers to build. If unspecified, build all drivers.')
+option('enable_libs', type: 'string', value: '', description:
+       'Comma-separated list of libraries to explicitly enable.')
 option('enable_driver_sdk', type: 'boolean', value: false, description:
        'Install headers to build drivers.')
 option('enable_kmods', type: 'boolean', value: false, description:
-- 
2.40.1